A phosphor bronze bore brush in .20 size with an English Parker Hale thread, made to fit a .177 cleaning rod. Phosphor bronze bristles are stiff enough to scrub powder fouling and lead out of the rifling but softer than barrel steel, so they do not damage the bore. Fit it to the rod, apply a little bore solvent, and run it through the barrel a few times before following with patches or a mop. This item is being discontinued by the supplier.