Buffer Tube Castle NutThe AR 15 Mil Spec Castle Nut is an essential component of the buffer tube assembly of an AR 15 rifle. Its main function is to secure the buffer tube to the lower receiver of the AR 15. It is compatible with most standard AR 15 stocks, making it easy to install and use with your existing set up. The Castle Nut provides a solid, stable platform for your buffer and spring, ensuring reliable operation and improved accuracy. Note: This castle nut does not