Section 23.3 - Application procedures and requirements(a) Before MSHA will undertake an active investigation leading to approval of any telephone or signaling device, the applicant shall make application by letter for an investigation leading to approval of the device. This application shall be sent to: U.S. Department of Labor, Mine Safety and Health Administration, Approval and Certification Center, 765 Technology Drive, Triadelphia, WV 26059, together with the required drawings, one complete telephone or signaling device, and instructions for its operation. Fees calculated in accordance with part 5 of this title shall be submitted in accordance with § 5.40 .(b) Where the applicant for approval has used an independent laboratory under part 6 of this chapter to perform, in whole or in part, the necessary testing and evaluation for approval under this part, the applicant must provide to MSHA as part of the approval application:(1) Written evidence of the laboratory's independence and current recognition by a laboratory accrediting organization;(2) Complete technical explanation of how the product complies with each requirement in the applicable MSHA product approval requirements;(3) Identification of components or features of the product that are critical to the safety of the product; and(4) All documentation, including drawings and specifications, as submitted to the independent laboratory by the applicant and as required by this part.(c) An applicant may request testing and evaluation to non-MSHA product safety standards which have been determined by MSHA to be equivalent, under § 6.20 of this chapter, to MSHA's product approval requirements under this part. 68 FR 36421 , June 17, 2003, as amended at 70 FR 46343 , Aug. 9, 2005; 70 FR 48872 , Aug. 22, 2005; 73 FR 52212 , Sept. 9, 2008