The RCBS Universal Hand Priming Tool Replacement Tray is perfect if you have lost or damaged the original tray, or if you just want to have an extra on hand to speed up the priming process. The square shape of the tray will accommodate most current primer packaging. The replacement tray also features a sliding primer shut off gate to keep primers from sliding out while loading or inserting the tray into the priming tool. This tray can also be used as an upgrade to the round tray design of the original RCBS hand priming tool, Product# 329291. Notes: Works with all brands of large and small rifle and pistol primers