WOOL BORE MOPS by BROWNELLS are designed for 20 gauge shotguns, made from virgin wool to hold bore cleaner or oil effectively.
The wool mop adapts to rifling grooves due to its natural springiness, and the brass shank and coupling are looped and twisted to prevent scratching the bore.
These mops are 2-7⁄8" (7.3cm) long with a 5⁄16"-27 thread, specifically tailored for thorough cleaning on both ends of the shotgun barrel.