FEATURES: Mil Spec, Multi-Cal Engraved, Semi-Auto MATERIAL: 7075 T6 Aluminum Forging FINISH: Type 3 Hard Anodized, Black COMPATIBILITY: All AR15 Calibers TREATMENT: Non RF85 ADDITIONAL NOTES: Accepts 3/4″ and 1″ Grip Screws, Takedown Pin Hole Threaded, Upper Receiver Threaded Hole †Added upper tension screw- Tension screw is installed/removed through the top of the lower. It is suggested that the screw should be removed for baked on finishes to avoid damage to the nylon tip. †Threaded rear takedown pin hole #4-40 †Enlarged magwell chamfer (flare) †Radius transition from trigger guard slot to trigger area †Radius rear trigger guard lugs †Thread grip screw hole all the way through †Improved machine deburring