Your 20 gauge bore brush scrubs the fouling - this cotton bore mop absorbs it and carries it out of the barrel. The densely packed 100% cotton head absorbs solvent and trapped residue in a single pass, leaving your 20-gauge bore clean and ready for a light coat of oil.
The 20 gauge's smaller bore (0.615") means a gun cleaning mop sized precisely for it matters. An oversized mop drags and bunches; an undersized one skips over residue. This bore mop fits the 20 GA bore snugly, so the cotton makes full contact with the bore walls and picks up every bit of loosened carbon and plastic wad fouling.
Use it two ways: wet with solvent after brushing for bore cleaning, then dry or lightly oiled for protection. Wash and reuse until the cotton wears thin. This shotgun cleaning mop finishes what the brush started - quick, effective, done.