The Fortis LE Lightweight Enhanced AR-15 End Plate uses the K1 tapered castle nut locking system. The K1 locking system uses a castle nut with a taper to friction lock onto the end plate that ensures it won’t back off over time without the need for staking, set screws, or ratcheting. Both the castle nut and end plate are machined from 7075-T6 aluminum. It also features a 360° QD sling swivel slot. The end plate features a black anodized finish and the castle nut has a gold anodized finish. Improve your AR-15 while improving the look with the Fortis K1 End Plate System.