The Lee APP Reloading Press and Deluxe APP Reloading Press are equipped with specialized shellholders designed specifically for use with these presses. These shellholders are not compatible with other Lee reloading presses. On the other hand, X-Press Shellholders are designed to match the same numbers as Lee Universal Shellholders, meaning they will fit the same cartridges. This compatibility makes X-Press Shellholders a versatile option for users who need a wide range of cartridge options for their reloading setup.