Check the listing for details. Barrel End - 1/2" bore - for non-threaded barrels - 1/2-28 TPI. Condition: New. Listed at 19.95 USD. Convert your 1/2" diameter non-threaded barrel to a standard 1/2-28 thread for all your end-of-barrel accessories. If you want to get the full fun factor out of your firearm, you need to be able to mount any 1/2-28 threaded accessory such as our muzzle brake, flash suppressor/compensator, or ANY other legal item. This thread adapter easily attaches to the factory finished plain muzzle. The outside diameter is 1 inch. This bore is .9 deep and has 2 set screws that are flush when tightened. Super simple and very effective. If your front sight is more than 1 inch behind the muzzle, this will still work. *** If you can measure your barrel, please do so and ensure it measures .500 inch or 12.7mm.*** This item is a lot less expensive than going to a machinist or gunsmith. You can install it yourself in minutes, and it can be taken off quite easily.Features1/2-28 TPI x 5/8 longBlack oxide finish for years of trouble free service.Thru bore will work for up to .25 CAL.This may fit other barrels, but is intended solely for 1/2" diameter barrel, plain muzzle.Designed, developed, and manufactured in the USA. Note: You will need to purchase the end-of-barrel accessory and crush washer separately