The Lock-Out Die detects a no powder or double charge condition in the progressive reloading process. It locks up halting the travel of the ram and alerting the reloader to the problem so the cause can be corrected. It will not let reloaders continue without removing the improperly charged cartridge. The Lock-Out Die is for use with straight-wall pistol calibers 9mm and larger and only on progressive reloading presses. - For use with straight-wall pistol calibers 9mm and larger and only on progressive reloading presses