This is the same rail used to fullfill contracts for the Federal Bureau of Investigation (FBI). Its strength, modularity and M-Lok compatibility gives users the capabilities needed to successfully complete the mission at hand. These rails are purpose-built and feature integrated M1913 picatinny rail sections at the fore of the rail in the 3, 6 and 9 o'clock positions. The Picatinny rail on the bottom of the rail, or the 6 o'clock position, is elongated in this version to accommodate accessories more comfortably. Maximum venting for heat dissipation also dramatically reduces the rails overall weight, while maintaining its same strong and rigid platform. The MK4 M-LOK rail f Mfg: Geissele Automatics