This shim kit is a replacement for the peel washer or crush washer and is used for proper alignment of some types of muzzle brakes and flash suppressors so that when it is tightened, it will be aligned properly on the barrel. New muzzle brakes often come with the necessary washers, nuts, or shims to mount them with. But some don't and sometimes replacements are needed if one is damaged or if installing a muzzle brake on a different gun.
While Peel washers require you to heat them and then peel off seperate layers of the washer to get to the desire thickness, a Shim Kit is much simpler. There is no heating or peeling of layers needed. Just install the necessary combination of shims to get the precise alignment you need. Additionally, the shims are re-usable unlike crush washers and you can use the right combination of shims to avoid over torqueing your barrel.
Kit includes 1 large shim, 8 medium shims, and 1 small shim.
* 1/2" Shims work on any barrel with 1/2" diameter threads such as 1/2x28 which are standard on .223/5.56mm barrels. 1/2x28 and 1/2x36 threads are also used on some pistol caliber barrels as well as other rifle calibers.