AT3 Tactical Castle Nut for AR-15 Buffer Tubes Pink. With standard cuts for use with armorers wrench and smaller cuts for staking the castle nut and endplate for a secure hold this part does everything it should at a good price. If youre in need of a spare for a new build or replacing a damaged component this one is right for you. You can also add a little more color to your black rifle with with your choice of Cerakote finish. Specifications for AT3 Tactical Castle Nut for AR-15 Buffer Tubes: Manufacturer: AT3 Tactical Gun Model: AR-15 Included Accessories: Standard Fabric/Material: Steel Features of AT3 Tactical Castle Nut for AR-15 Buffer Tubes Finish: Black or colored Cerakote finishes Thread: Mil-Spec Compatible with armorers wrench Package Contents: AT3 Tactical Castle Nut for AR-15 Buffer Tubes What firearm models does the manufacturer say AT3 Tactical Castle Nut for AR-15 Buffer Tubes is compatible with? The manufacturer says that AT3 Tactical Castle Nut for AR-15 Buffer Tubes is compatible with AR-15AT3 Tactical AT3-Castle-01-PNK: Castle Nut for AR-15 Buffer Tubes Pink