Designed specifically for Dewey Coated Rods. The Delrin guides fit all handguns and rifles of the appropriate caliber. Designed to keep cleaning rod centered in bore and protect the barrel crown when it is not possible to clean the firearm from the breech. They are recommended for use with coated cleaning rods, but clearance is provided for use with any type cleaning rod. Measures 3/4" overall length, knurled surface outside of bore is 3/8" thick.