The Caldwell Mag Charger Universal Pistol Loader has adjustable side shims to align magazines of any width for optimal use. Shims are labeled with numbers for quick adjustment. Works with both single-stack and double-stack magazines. Loads 9mm, 10mm, .357, .40 and .45cal ammo. Simple to use - just drop in a round and squeeze the trigger. Lock knob keeps virtually any size magazine secure. Two times faster than hand loading; half as much force than loading by hand.