Fortis Manufacturing LE Lightweight Enhanced AR15 End Plate System K2 Locking Lever Red Castle Nut. With two lockdown systems (K1 and K2) we've engineered a solution to install the castle nut onto the end plate that is not only robust but also stands true to brand of innovation and ingenuity. The K2 system utilizes a locking lever design that seats itself through a designed slot on the bottom of the end plate and into corresponding cutouts on the castle nut. This ultra precision fit allows the castle nut to seat itself into place without the need of staking the end plate. No set screws no backing out and no failures. All of these features at only .53 oz / 15 grams Specifications for Fortis Manufacturing AR-15 LE Locking Lever Castle Nut/End Plate K2 System: Manufacturer: Fortis Manufacturing Finish: Milspec Anodized Fabric/Material: 7075-T6 Aircraft Grade Aluminum Hand: Ambidextrous Gun Make: AR Platform Gun Model: AR-15 Weight: 0.53 oz Quantity: 1 Condition: New Features of Fortis Manufacturing AR-15 LE Locking Lever Castle Nut/End Plate K2 System Lightweight design at only .53 oz / 15 grams total Quick Detach Socket - 360 degree rotational locking interface No set screws or ratcheting system Package Contents: Fortis Manufacturing AR-15 LE Locking Lever Castle Nut/End Plate K2 System What firearm models does the manufacturer say Fortis Manufacturing AR-15 LE Locking Lever Castle Nut/End Plate K2 System is compatible with? The manufacturer suggests that Fortis Manufacturing AR-15 LE Locking Lever Castle Nut/End Plate K2 System is compatible with AR-15Fortis Manufacturing LE-BLK-K2-RED: LE Lightweight Enhanced AR15 End Plate System K2 Locking Lever Red Castle Nut