48 C.F.R. § 211.170
211.170 Use of proprietary specifications or standards.
A justification and approval is required to use proprietary specifications and standards—
(1) When using sealed bidding or negotiated acquisition procedures (see 206.302-1(S-70) for justification requirements); or
(2) When using the simplified procedures for certain commercial products or commercial services at FAR 13.5 (see 213.501(a)(ii) for justification requirements).