Unlike other seaters, ours is designed so the operator can elminate all slop when working with a specific cartridge. That translates into perfect seating, reliable ignition and reduced misfires. No additional shellholders are required. The E-Z-Just jaws close to securely grip most modern rifle and pistol cases with a rim thickness of .045" to .072". Other features include a built-in primer flipper tray. Large and small primer tubes have an open slot and primers stack sideways for added safety.