The SLR Enhanced Castle Nut and Endplate works with all multi position buffer tubes. The Dimpled Castle nut allows secure retention without the need for staking; 2 set screws on end plate secure nut by lining up with dimples. This system allows for easy dissasembly and repeated use of nut and end plate FeaturesCastle nut , Receiver end plate and HardwareSLR 4140 Receiver end plate with Limited rotation QD and Melonite finishSLR 4140 Castle nut with Melonite finish