The RCBS Hand Priming Tool not only seats primers quickly, a safety mechanism separates the seating operation from the primer supply to reduce the risk of tray detonation. It fits in a reloader's hand for portable primer seating and primer tray installation requires no contact with the primers. The tool uses the same RCBS shell holders (post-1980) as RCBS presses. It's made of durable cast metal and includes large and small primer plugs.