Description FEATURES: Mil Spec Multi-Cal Engraved Semi-AutoMATERIAL: 7075 T6 Aluminum ForgingFINISH: Type 3 Hard Anodized BlackCOMPATIBILITY: All AR15 CalibersTREATMENT: Non RF85ADDITIONAL NOTES: Accepts 3/4 and 1 Grip Screws