RCBS #90306. RCBS Case Trimmers are designed to be user friendly and provide very accurate results. These shellholders are required to hold the brass cases while they are being trimmed. Works with: RCBS Trim pro, manual and power case trimmer only. Fits: .22 Remington Jet, 5.6mm x 50 Rimmed, .256 Winchester Magnum, .357 Magnum, .357 Remington Maximum, .38 Smith & Wesson, .38 Special.