Forster Original Case Trimmer Collets #1, #2, #3, and #4 Collets to fit most popular cartridges on the original Forster Case Trimmer. See our Forster Products Page for cartridge/collet fitting information. The collet grips the rim of cartridge brass on center in the Forster Case Trimmer. Each collet fits 2-3 different rim diameters and many cartridges have the same rim diameter. For Example: Collet #1 fits 223 Remington, 308 Winchester, 338 Winchester Magnum and all other cartridges with the same rims. Collet #2 fits 22 Hornet, 32-20, 30-30 Winchester, 6.5mm BRM, and all other cartridges with the same rims. Collet #3 fits 22 PPC, 6mm PPC, 40 S&W, 30-40 Krag and all other cartridges with the same rims. And Collet #4 Fits 300 Norma Mag, 375 H&H, 338 Lapua Mag, 45-70 and all other cartridges with the same rims. We have links to charts where you can select your collet by the cartridge or by the rim diameter... See our Forster Products Page.