30 C.F.R. § 57.22222
Ventilation materials (I-A, I-B, I-C, II-A, III, V-A, and V-B mines)
Brattice cloth and ventilation tubing shall be approved by MSHA in accordance with 30 CFR part 7, or shall bear a BC or VT acceptance number issued by the MSHA Approval and Certification Center.