The auto primer tube is designed for use rcbs 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 ii and reloader special presses.Note: this item is not for use with rc supreme.Capacity: 100 PrimersType: Auto Primer Feed TubeCaliber: For Rock Chucker Press/JR & Reloader Special PressSize: LargeQuantity: 1Function: Feed PrimersCompatible With: Rock Chucker II and Reloader Special Presses