Bravo Company 3 Polymer Picatinny Rail Section, MLOK Compatible, Black BCM-MCMR-1913-N3-BLK Bravo Company's BCM 3 Inch Nylon Picatinny Rail Section" M-Lok Compatible" is made of lightweight impact resistant polymer. It is made to the Mil-Standard 1913 Picatinny Arsenal Specifications and it features a snag resistant design while retaining Mil-Standards.