The RCBS Hand Priming Tool not only seats primers quickly, it s also the safest. A patented safety mechanism separates the seating operation from the primer supply, virtually eliminating the possibility of tray detonation. It fits in your hand for portable primer seating and the primer tray installation requires no contact with the primers. Uses the same RCBS shell holders (post-1980) as RCBS presses. This hand priming tool is made of durable cast metal and includes large and small primer plugs.