Designed for the RCBS MatchMaster Precision Case Trimmer, these precision-designed collets ensure your cases stay secure, giving you a precise and repeatable trim every time. Available in four sizes, covering a wide range of cartridges. Collet #1 - .379, .473, .532 Diameters: 222 Rem. Mag 223 Rem 225 Win 22-250 220 Swift 243 Win 6mm Dasher 6A-47 Lapua 6XC 244 Rem 6mm B.R. Rem. 257 25-06 264 Win. Mag 260 Rem 6.5A-47 Lapua 6.5 Creed 6mm Creed 6mm SLR 6.5A-57 Mauser 6.5mm Win 6.5 Jap Mauser 6.5A-55 Swede 6.5A-55 SKAN 270 Win 270 Savage 270 Gibbs 270 Wby 270 Ackley 7A-57 Mauser 7mm Wby 7mm-08 280 Rem 284 Win 7mm Rem. Mag 7mm B.R. Rem 30-06 308 Win 300 Win Mag 300 Sav 303 British