Yes this is a dead blow/sliding weight buffer - Kaw Valley Precision Stainless Steel Heavy Tungsten Buffer

This is the buffer you want for an ar9 build to minimize risk of out of battery detonation. Visit blowback9's website and his Reddit posts in ar9 for more information.

Seems like a solid very high quality buffer and I feel much better about the risk of oob using this buffer versus a heavy buffer without sliding weights that is likely to result in bolt bounce