The Otis bore brush and mop combo pack includes 1 bronze bore brush and 1 cotton bore mop. Otis brushes have a proprietary Tufcor(R) core wire that is corrosive-resistant with a tighter twist for better bristle retention and brush life. With twice the fill of other brushes and bristles right to the end, you get superior quality and precision cleaning every time. The bore mops are densely packed, highly absorbent cotton. Cleans: .30-06/.300/30-30/.308cal/7.62mm Length: 2 Inch Thread: 8-32 Includes: 1 Bronze Brush / 1 Cotton Bore Mop Our caliber-specific brushes have the size indicated on the stem, ensuring you grab the right brush every time.