The Geissele Automatics 05650S features the Super Modular Rail MK16. This product is perfect for the most discerning shooters because it has outstanding performance. The updated Geissele Barrel Nut design allows it to be mounted on your AR-15 upper with ease, resulting in an easy installation and maintenance process, while also providing excessive rigidity.The MK16 comes with anti-rotation tabs and set-screws to prevent your rail from rotating under any conditions, even during the most demanding use. The incorporation of M1913 picatinny rail on top and M-LOK slots on all quadrants makes it highly customizable, perfect for accommodating all your accessories.For strength, rigidity, and lightweight characteristics, the Geissele SMR MK16 is precision-engineered using 7000 Series Aluminum. To ensure durability, it is completed with Type-3 Hardcoat anodized finishing.