Cross Armory Castle Nut Wrench for AR-15 and AR-10 High Carbon Steel Black Small. Torture tested and proven to outlast all other competing castle nut wrenches Each wrench features a rubberized grip for improved performance 2X thicker material case hardened High-Carbon Steel and the reliability safety and comfort you have come to expect form Cross. Performs the job of a: Mil-Spec castle nut wrench and standard length receiver extension removal wrench. Specifications for Cross Armory Castle Nut Wrenches: Manufacturer: Cross Armory Color: Black Finish: Black Length: 6.75x1.25 mm Caliber: Universal Gun Model: AR-10 AR-15 Fabric/Material: Carbon Steel Weight: 4 oz Condition: New Features of Cross Armory Castle Nut Wrenches Best and strongest castle nut wrench on the market Fits all AR-15 and AR-10 castle nuts 2x thicker than standard castle nut wrench Made from ultra high strength high-carbon steel Case hardened and black oxide coated Package Contents: Cross Armory Castle Nut Wrenches What firearm models does the manufacturer say Cross Armory Castle Nut Wrenches is compatible with? The manufacturer says that Cross Armory Castle Nut Wrenches is compatible with AR-15 AR-10Cross Armory crCN-tool: Castle Nut Wrench for AR-15 and AR-10 High Carbon Steel Black Small