Arisaka Defense MCX Zero Retention Clamp Fits Sig Sauer MCX LT Standard Handguard Anodized Finish Black. The Patented Arisaka Zero Retention Clamp (ZRC) greatly reduces zero shift for lasers and iron sights that are mounted on the handguard of the MCX Spear LT. This version is designed for the MCX Spear LT chambered in 5.56 7.62x39 and 300BLK. The Rattler is not currently supported. The MCX Spear LT handguards are not adequately secured to the upper receiver. This allows the handguard to flex significantly causing a laser or front sight zero to change when minor pressure is applied to the handguard. A shift of 5 mils or more is possible by pushing on the handguard with your support hand while the rifle is shouldered. Additionally the zero does not always return to it's original position once pressure is removed from the handguard. The Arisaka ZRC consists of exterior clamps that thread into a special U-bracket. The U-bracket engages the extended upper receiver underneath the handguard. This secures the handguard tightly to the upper receiver across two axis greatly reducing or even eliminating zero shift. The U-bracket does not touch the barrel or gas system preserving the free-floated barrel. The ZRC clamps are contoured to provide minimal interference with the user's hands while gripping the handguard. Arisaka is not responsible for any damage caused by improper installation. The ZRC must be uninstalled before removing the handguard from the rifle. Specifications for Arisaka Defense MCX Spear LT Standard Zero Retention Clamp: Manufacturer: Arisaka Defense Gun Make: SIG Sauer Gun Model: Sig Sauer MCX-SPEAR LT Color: Black Finish: Anodized Fabric/Material: 6061-T651 aluminum Gun Type: Rifle Condition: New Case Finish: Anodized Handle Color: Black Blade Finish: Anodized Caliber: 7.62x51mm NATO 5.56x45mm NATO .300 AAC Blackout Handle Finish: Anodized Weight: 1 oz Package Contents: Arisaka Defense MCX Spear LT Standard Zero Retention Clamp Arisaka Defense MCX Spear LT Standard Zero Retention Clamp Black ZRC-SPEAR-LT