Extra-thick, kinked, phosphor bronze wire gives the hard scrubbing action needed to cut through the toughest crud in your bores. You'll have to push like the dickens, but the results will be well worth it. Bristles are Extra-Thick phosphor Bronze and will not scratch bores. Great for removing stubborn carbon deposits. Rifle Brushes are 3.25" Long and use 8-32 male Threads Rifle Brushes .54 and .58 have 10-32 Male Threads Pistol Brushes are 2.88" Long and use 8-32 Male Threads Shotgun Brushes are 2.88" Long and use 5/16"-27 Male Threads