This is a one-for-one replacement for the magazine that came with your RugerA(R) Mark IV(TM) 22/45(TM) when it was new. The RugerA(R) Mark IV(TM) 22/45(TM) replacement magazine meets the factory specs for correct fit and reliable feeding in your pistol. The sturdy steel mag body has a slick polished steel finish. The black polymer base plate protects the mag, while the polymer follower can be manually lowered for easy loading by operating the side button. For use only in RugerA(R) Mark IV(TM) 22/45(TM) .22 LR pistols, including Mark IV(TM) 22/45(TM) Lite NOT recommended for use in Mark III(TM) 22/45(TM) pistols 10-round capacity T Mfg: Ruger