Over the years these brushes have been used to set world records across the world. With exceptional bore cleaning ability, they are also a safe for your bore. All Pro-Shot Benchrest Bore Cleaning Brushes are specifically sized for each caliber/mm, with each brush being over-sized for extended life and maximum cleaning power!Features : Superior Stiff Bristles with Extra Thick Fill Precision Rifle #8-32 Threads Made in the USA