"Benchrest Quality",tm brush consists of a Brass Core, Bronze Bristles, Brass Coupling, Looped End, Oversized Diameter, and Caliber or MM Specific. The Ultimate BORE BRUSH that out performs and lasts longer than the competition. YOUR FIREARMS DESERVE THE BEST IN GUN CARE, invest in a Pro-Shot "Benchrest Quality"tm bore brush! ,BR> Designed for competition shooters to withstand frequent use. Pro-Shot’s Benchrest Quality Brush has been used for many years with several world records to its credit. This bore brush is exceptional for bore cleaning with superior cleaning ability and it will not harm the bore. All Pro-Shot Benchrest Bore Cleaning Brushes have a specific size for each caliber with each brush being oversized for extended life. All brushes have #8-32 thread, except .17 & .20 Cal. which is #5-40 thread.