Montana X-Treme Cleaning Brushes are the toughest nylon brushes in the
industry. They are made with very stiff, heavy duty bristles and a solid
brass core to assure your firearms will get a superior cleaning with
minimal effort on your part. Standard 8 x 32 thread (.17 and .20 Cal
brushes have a 5 x 40 thread, and shotgun brushes have a 5/16 x 27
.20 Caliber Rifle.