Geissele 05-430S 10" M-LOK MK4 Federal DDC Super Modular RailGeissele’s Super Modular MK4 Rail is used by the Federal Bureau of Investigation due to its strength, modularity, and M-LOK compatibility. It features M1913 picatinny rails in the 6 o’clock and 12 o'clock positions, as well as shorter M1913 picatinny rails in the front 3 o’clock and 9 o'clock positions. This accommodates a massive amount of accessories such as optics, iron sights, fore-grips, and tactical lights/lasers. The Bottom picatinny rail is also elongated to mount accessories more comfortably. In addition to the picatinny rails, the Super Modular MK4 Rail features M-LOK slots in the 3, 6, and 9 o’clock positions as well as in the upper 45° quadrants. Not only do the M-LOK rails provide more mounting locations, they also help reduce weight and provide more ventilation to help cool off the barrel during extended firing sessions. Features of the Geissele Super Modular MK4 Rail: M1913 picatinny rails in the 3, 6, 9, & 12 o’clock positionsM-LOK slots in the 3, 6, and 9 o’clock positions & in the upper 45° quadrantsLightweight designMaximum ventilation on the barrel Geissele 10" M-LOK MK4 Federal DDC Super Modular Rail 05-430S