The Super Modular Rail MK4 M-LOK(TM) is Geissele's ultra-lightweight M-LOK option. 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. 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 features M-LOK slots at the 3, 6 and 9 o'clock positions as well as the upper 45Adeg quadrants. This allows the user to keep the weight on the rail system down, while keeping the modularity and versatility to attach accessories as necessary. Barrel nut wrench & gas block not in Mfg: Geissele Automatics