The Auto Primer Tube is designed for use RCBS(R) Automatic Primer Feed, which drops primers one at a time into the primer plug and sleeve. It helps stop misfires, as greasy fingers never need to touch primers, and the nylon primer pick-up keeps primers from falling out. It has a tube capacity of 100 primers and fits the Rock Chucker(R) II and Reloader Special Presses. Note: Not for use with RC Supreme.Features :100 primer capacityHelps prevent misfiresNylon primer pick-up