This attachment creates a constant flow of cutting fluid (from your lathe) starting from the muzzle and flowing to the chamber of a barrel being reamed on a lathe. The pilot and reamer are constantly lubricated, and sharp metal chips are flushed back out of the chamber. This system creates a cooler cutting environment, reduces stresses on the tooling and barrel and eliminates possible bore damage from sharp metal chips. Fits barrels from 1/4" to 1.3" in diameter at the muzzle and mounts on the last 2-1/2" of the muzzle end of the barrel. Installs in about 15 seconds and is guaranteed not to leak.