WARNING LETTER

Hong Qiangxing Shenzhen Electronics Limited MARCS-CMS 718112 — October 28, 2025

Delivery Method:: VIA Electronic Mail
Product:: Medical Devices

Recipient:: Recipient Name

Zhu Shi Hong; Recipient Title

Vice President and Management Representative; Hong Qiangxing Shenzhen Electronics Limited; 2F, Yongcheng Boulevard
Xicheng Industrial Area, Xixiang Road
Bao'an Qu
Shenzhen Shi
Guangdong Sheng, 518126
China; 1049936065@qq.com

Issuing Office:: Center for Devices and Radiological Health; United States

October 28, 2025

WARNING LETTER
CMS #: 718112

Dear Zhu Shi Hong:

During an inspection of your firm located in Shenzhen, Guangdong, China, on August 4, 2025, through August 7, 2025, an investigator from the United States Food and Drug Administration (FDA) determined that your firm manufactures wrist blood pressure monitors, Belifu TENS001 (Model SM9126), and various transcutaneous electric nerve stimulators (TENS) and powered muscle stimulator (PMS) devices. Under section 201(h) of the Federal Food, Drug, and Cosmetic Act (the Act), 21 U.S.C. § 321(h), these products are devices because they are intended for use in the diagnosis of disease or other conditions or in the cure, mitigation, treatment, or prevention of disease, or to affect the structure or any function of the body.

Quality System Regulation Violations
This inspection revealed that these devices are adulterated within the meaning of section 501(h) of the Act, 21 U.S.C. § 351(h), in that the methods used in, or the facilities or controls used for, their manufacture, packing, storage, or installation are not in conformity with the current good manufacturing practice requirements of the Quality System regulation found at Title 21, Code of Federal Regulations (CFR), Part 820. We received responses from Zhu Shi Hong, Vice President and Management Representative, dated August 21, 2025, September 26, 2025, and October 8, 2025, concerning our investigator's observations noted on the Form FDA 483 (FDA 483), List of Inspectional Observations, which was issued to your firm. We address these responses below, in relation to each of the noted violations. These violations include, but are not limited to, the following:

1. Failure to establish and maintain procedures to control the design of the devices to ensure that specified design requirements are met, as required by 21 CFR 820.30(a). Specifically:

a) Failure to adequately validate device software, as required by 21 CFR 820.30(g). Your firm failed to adequately verify and validate the operating software for the TENS and PMS Model SM9109A.

This is a repeat violation from the July 2016 inspection.

We reviewed your firm's August 21, 2025, September 26, 2025, and October 8, 2025, responses and conclude that they are not adequate. In these responses, your firm provided a corrective and preventive action (CAPA) report. The report identified the root causes as 1) lack of specific inspection and confirmation of the software during the burning process, and 2) lack of establishment of control procedures for the software burning process.

Your firm identified CAPAs to be taken as 1) establish the "Software burn-in Procedure," requiring the burn-in operators to confirm the burn-in version and conduct the initial burn-in inspection, carry out the burn-in process only after the initial inspection is passed, and conduct inspections and record the burn-in status every hour during the burn-in process; 2) record the software burn-in information, initial inspection results, and the burn-in process in a “Software burn-in Record;” and 3) conduct training for the engineering department on the new procedure. In the response dated October 8, 2025, your firm provided a copy of the newly established “Software Burning Procedure.” However, the response does not address retrospective review to ensure that software on previously manufactured devices is validated.

b) Failure to adequately establish procedures for design change, as required by 21 CFR 820.30(i). Your change control procedures do not adequately ensure that the description of the change, the reason for the change, and the impact of the change is adequately evaluated and that the evaluation and results are documented. For example, three out of three change records reviewed involving changes to the TENS and PMS devices [Model SM9109A (RL-109A-6A1) and Model TENS7000 (RL-069)] and the Model SM 9019 (RL-0198-2C1) Remote Controller documented in ECN20240626001, ECN20231026001, and ECN20250425001 lacked adequate documentation of the change description, the reason for the change, and the evaluation of the impact of the change.

We reviewed your firm's August 21, 2025, September 26, 2025, and October 8, 2025, responses and conclude that they are not adequate. In these responses, your firm provided a CAPA report. The report identified the root causes as 1) a lack of planning for changes, resulting in insufficient information during the change process and absence of verification requirements, 2) a lack of planning for the changes due to the failure to implement an engineering change request (ECR) review or to effectively control the change process and verification, and 3) the absence of specific requirements for the execution and approval of ECR, so that verification was missing during the change process.

c) Failure to establish and maintain procedures for validating the device design, as required by 21 CFR 820.30(g). Your rationale for the sample size used in design validation for the low frequency Electronic Pulse Therapy Device Model SM9109A (RL-6A1) is not documented. Additionally, the device samples used in design validation were manufactured by the engineering department and were not produced under defined operating conditions as initial production units, lots, or batches or their equivalents. This is a repeat violation from the July 2016 inspection.

d) Failure to establish and maintain procedures for verifying the device design, as required by 21 CFR 820.30(f). Your rationale for the sample size used in design verification for the low frequency Electronic Pulse Therapy Device Model SM9109A (RL-6A1) is not documented. This is a repeat violation from the July 2016 inspection.

e) Failure to ensure that the design history file demonstrates that the design was developed following the requirements of 21 CFR 820, as required by 21 CFR 820.30(j). Your design verification and design validation for the low frequency Electronic Pulse Therapy Device Model SM9109A (RL-6A1) are inadequate in that the raw data in support of the design verification and validation are not documented, and that there are not documented manufacturing records for the samples used in verification and validation. This is a repeat violation from the July 2016 inspection.

We reviewed your firm's August 21, 2025, September 26, 2025, and October 8, 2025, responses and conclude that they are not adequate. In these responses, your firm provided a CAPA report. The report identifies the root causes as 1) a lack of planning for changes, resulting in insufficient information during the change process and absence of verification requirements, 2) a lack of planning for the changes due to the failure to implement an ECR review and the change process and verification were not effectively controlled, and 3) the absence of specific requirements for the execution and approval of an ECR so that verification was missing during the change process.

Your firm identified the following CAPAs in response: 1) update the COP-414-01 change control procedure and add the requirement that an ECR review must be conducted before the change, and 2) include in the ECR content the source of the change requirement, comparison of the device before and after the change, evaluation of the safety and effectiveness of the change impact, assessment of foreseeable risks arising from the change, and the change verification plan, including sampling plan, inspection basis record requirements, and sample requirements. Additionally, the report states that training will be conducted on the new "Change Control Procedure" and requirements of the ECR. The response dated October 8, 2025, includes evidence of the above described CAPAs, including an updated “Change Control Procedure.” However, this response does not address systemically inadequate design verification and validation reports, including a lack of documentation of raw data in support of the design verification and validation and a lack of documented justification of sample size. Additionally, it does not ensure that device samples used in design verification and validation are manufactured under defined operating conditions as initial production units, lots, or batches, or their equivalents, or that documented manufacturing records confirm the samples are used in verification and validation under normal manufacturing conditions in cases when there is not a design change. Similarly, your response does not address retrospective review to ensure design verification and validation of any devices already made and/or in storage.

2. Failure to adequately establish procedures to control product that does not conform to specified requirements, as required by 21 CFR 820.90(a).

Specifically, COP-830-01, “Control of Nonconforming Product,” does not ensure that the disposition of nonconforming product is documented or include a justification for use of nonconforming product. For example, a justification for use of nonconforming products is not documented in the Nonconforming Review and Disposal Form No. 20240103001. The dispositions of nonconforming products in Nonconforming Review and Disposal Forms No. 2025010803 and No. 2024082001 were also not documented.

Further, this is a repeat violation from the July 2016 inspection.

We reviewed your firm's August 21, 2025, September 26, 2025, and October 8, 2025, responses and conclude that they are not adequate. In these responses, your firm provided a CAPA report. Your firm identified root causes including that 1) the material on nonconformance handling forms identified in the inspection all underwent special acceptance and were approved but the special acceptance details were not recorded in the records; 2) there is no dedicated special acceptance review form established in the process of handling nonconforming products, so the special acceptance information is not reflected; and 3) there are no detailed procedures on the special acceptance process in COP-830-01, “Control of Nonconforming Product,” resulting in incomplete special acceptance information.

Your firm identified CAPAs as: 1) establish the "special acceptance request" requiring that the special acceptance process must describe and approve the information and quantity, and specify any expected risks of the special acceptance materials; 2) reapply for special acceptance for the nonconforming product handling forms identified during the inspection to ensure the completeness of the special acceptance information; and 3) revise COP-830-01, “Control of Nonconforming Product,” to add the "special acceptance request" requirement and stipulate that direct use, selective use, and production processing all fall under the "special acceptance" process. The "special acceptance request" form should be filled out by the department with special acceptance requirements, including the description of the nonconforming product, the expected risks generated by special acceptance, the special acceptance suggestions, and the quantity of special acceptance. After being approved by relevant departments and the management representative, special acceptance can be carried out.

In the response dated October 8, 2025, your firm provided evidence of the above described CAPA, including an updated COP-830-01 procedure with a section on a "Special Procurement Application," specifying conditions in which nonconforming materials can be used for specific purposes after appropriate approval. Your firm also provided copies of a "Special Acceptance Request" form, filled out per the "Special Procurement Application" process, for the specific cases referenced in this observation. However, the responses do not address retrospective review to ensure that any other previous nonconformance handling forms not reviewed during the inspection are also appropriately reviewed and documented according to the updated procedure.

3. Failure to adequately establish procedures for corrective and preventive action as required by 21 CFR 820.100(a).

Specifically, a) the corrective and preventive action procedures do not ensure that sources of quality data are adequately analyzed to identify existing and potential causes of nonconforming product or other quality problems; b) CAPA 2025022501 was not adequately investigated to identify corrective actions and the effectiveness of the actions taken was not verified; and c) the effectiveness of the actions taken in CAPA 2025060401 were not verified.

We reviewed your firm's August 21, 2025, September 26, 2025, and October 8, 2025 responses and conclude that they are not adequate. In these responses, your firm provided a CAPA report. Your firm identified the root causes for inadequacies in these two CAPA forms as 1) a delay in receiving complaint information from American distributors and confirmation of the problem which required no adjustment to the complaint from the distributor, and 2) a lack of stipulation in COP-821-01, “Customer Complaint Feedback Control Procedure,” for the handling of defective products after they are returned, such that the quality department did not update the CAPA, and 3) a lack of regulations in COP-630-01, “Facility and Equipment Management Procedure,” for the handling of facilities and equipment after adjustment, such that the engineering department did not conduct any verification after implementing a change resulting from a complaint.

Your firm’s proposed CAPA includes 1) re-examining the root cause analysis of the first CAPA form to confirm the fundamental reason for the problem that led to the returned product, 2) re-validating the corrective action and providing the investigation and verification results to the customer, and 3) revising COP-821-01, “Customer Feedback Control Procedure,” to add the requirement that "After the customer returns the defective products due to complaints, re-inspection shall be conducted to confirm whether the defects are consistent with the descriptions provided by the distributor or the user." Additionally, the actions include 1) carrying out small-scale trial production of the adjusted line speed of the packaging line to verify the effectiveness of the previous corrective action, and 2) updating COP-630-01, “Facility and Equipment Management Procedure,” and adding the requirement that "Facility and equipment should be adjusted according to production requirements. After the adjustment, it needs to undergo small-scale trial production verification to confirm the adjustment [is] effect[ive] before use." The response dated October 8, 2025, provided evidence of the above described CAPA, including copies of the revised CAPA forms and an updated COP-630-01 procedure. However, the responses do not address how your firm will validate the effectiveness of future CAPAs or include retrospective review to ensure effectiveness of other previous CAPA reports.

4. Failure to adequately establish procedures for receiving, reviewing, and evaluating complaints by a formally designated unit, as required by 21 CFR 820.198(a).

Specifically, the complaint handling procedures do not ensure that complaints are processed in a uniform and timely manner or that they are adequately investigated and evaluated for submission of a medical device report (MDR). For example, 4 out of 4 complaints reviewed were not adequately investigated and lacked documented MDR evaluation. One of the complaint records reviewed, Customer Complaint Form No. 23081101, included two separate reported malfunctions of two different TENS and PMS devices received on different dates from the same customer. Your firm failed to create separate reports to adequately process, investigate, and evaluate each complaint.

Your firm’s responses, dated August 21, 2025, September 26, 2025, and October 8, 2025, appear to be adequate. In these responses, your firm provided a CAPA report. Your firm identified root causes, including that the review requirements for the submission of an FDA MDR were not reflected on the customer complaint handling form, so the marketing department did not assess the MDR requirements. In one complaint (number 23081101), the customer mentioned both the ZX-518BM and the 587B device models, but the inventory checks were recorded on a single form. As there were no specific requirements in the complaint feedback control procedure for situations where a single complaint involved multiple device models or products, the investigation did not distinguish between them. Your firm identified CAPAs, including 1) revising the customer complaint handling form QR-821-05/00 to add the FDA MDR assessment requirements, 2) re-evaluating the customer complaints handling from 2025, 2024, and 2023 to determine whether an FDA MDR is necessary, 3) revising the customer feedback control procedure COP-821-01 to add information about MDR procedures, and 4) revising the customer feedback control procedure COP-821-01 to specify that if a complaint involves multiple products or different models, a separate investigation needs to be conducted for each product or model. In the response dated October 8, 2025, your firm provided evidence of the CAPA investigation, including an updated version of the COP-821-01 procedure.

5. Failure to adequately establish procedures for identifying product during all stages of receipt, production, distribution, and installation, as required by 21 CFR 820.60.

Specifically, during the walk through inspection, the investigator observed an unidentified box of what appeared to be in-process, partly assembled TENS and PMS units on a work bench and a case of unidentified in-process, semi-assembled TENS and PMS units stored on a pallet on the floor near a soldering workstation in the production room. In various areas, such as in the receiving/shipping and production rooms, there were unidentified, opened and half-opened boxes and a variety of materials and production and test equipment that your firm stated were obsolete and no longer in use.

Your firm’s responses, dated August 21, 2025, September 26, 2025, and October 8, 2025, appear to be adequate. In these responses, your firm provided a CAPA report. Your firm identified root causes including: 1) a failure of the production department to properly organize materials in time due to the large volume of production tasks and the abundance of materials, 2) a lack of production environment control measures that resulted in the production materials not being assigned to specific storage areas, and 3) a lack of production environment control procedures, leading to a lack of production environment inspections and the disorderly placement of materials.

Your firm identified CAPAs including 1) establish production environment control procedures to set requirements for the placement of materials in the production area and the cleanliness of the environment, and 2) establish a checklist for the production environment and conduct daily inspections of the production environment. In the response dated October 8, 2025, your firm provided evidence of the CAPA implementation, including a copy of the newly established "Production Environment Management Regulations" procedure and a production environment inspection record form demonstrating inspection of the production environment beginning in mid-August 2025.

Other federal agencies may take your compliance with the Federal Food, Drug, and Cosmetic (FD&C) Act and its implementation regulations into account when considering the award of federal contracts. Additionally, should FDA determine that you have Quality System regulation violations that are reasonably related to premarket approval applications for Class III devices, such devices will not be approved until the violations have been addressed.

Please notify this office in writing, within fifteen business days from the date you receive this letter, of the specific steps your firm has taken to address the noted violations, including an explanation of how your firm plans to prevent these violations, or similar violations, from occurring again. Include documentation of the corrections and/or corrective actions (which must address systemic problems) that your firm has taken. If your firm's planned corrections and/or corrective actions will occur over time, please include a timetable for implementation of those activities. If corrections and/or corrective actions cannot be completed within fifteen business days, state the reason for the delay and the time within which these activities will be completed. Please provide a translation of documentation not in English to facilitate our review. We will notify you regarding the adequacy of your firm’s response(s) and the need to re-inspect your firm’s facility to verify that the appropriate corrections and/or corrective actions have been made. If you believe that your products are not in violation of the FD&C Act, include your reasoning and any supporting information for our consideration as part of your response.

Your firm's response should be sent via email to Tushar Bansal, Ph.D., at CDRHEnforcement@fda.hhs.gov. Please include in the subject line, CMS case # 718112 when replying. If you have any questions about the contents of this letter, please contact: Tushar Bansal, Ph.D., at Tushar.Bansal@fda.hhs.gov.

Finally, you should know that this letter is not intended to be an all-inclusive list of the violations at your firm's facility. It is your firm's responsibility to ensure compliance with applicable laws and regulations administered by FDA. The specific violations noted in this letter and in the Inspectional Observations, FDA 483, issued at the close of the inspection may be symptomatic of serious problems in your firm's manufacturing and quality management systems. Your firm should investigate and determine the causes of the violations and take prompt actions to address any violations and bring the products into compliance.

Sincerely,
/S/

David McMullen, M.D.
Director
OHT5: Office of Neurological
and Physical Medicine Devices
Office of Product Evaluation and Quality
Center for Devices and Radiological Health

CC:
Mark Gordon
1800 Byberry Road Suite 905
Huntingdon Valley, PA 19006
920-601-9045
(b)(6)@outlook.com