These brass guides protect thecrowns of firearms that have tobe cleaned from the muzzle.Place the guide on your cleaningrod, start your patch orbrush into the barrel, and thenslide the guide down into themuzzle. The guide has an "O"-ring to keepthe brass guide cap off of the crown. Thereis plenty of clearance on the inside diameterof the guide to use any type of cleaning rod(Dewey, Parker Hale, Pro-Shot, etc.). Great for lever actions. Mfg: Dewey