This replacement magazine is a factory original from Smith & Wesson. Factory replacement parts are manufactured to the exact same specifications and tolerances and use the same manufacturing materials as the original parts which guarantees excellent fit and reliable operation. This magazine is designed for a flush fit on a full-size M&P handgun. It will also fit M&P Compact models, however it will stick out further than normal from the magazine well, leaving some of the magazine body visible. All these magazines have the same PVD finish on the body of the magazine. They are offered with polymer basepads in either black or brown to match the color of your factory M&P 45. Keeping a few extra factory magazines around is never a bad idea; extra magazines save loading time at the range and also serve as a backup for those days when you simply cannot remember where you put your primary magazine.