Built to hold 7 rounds of ammunition. Will only hold 9mm luger rounds. Constructed of stainless steel to assure this replacement magazine withstands most torture tests, also stainless steel is corrosion resistant. Embedded with a hi-tensile compression steel spring for a smooth feeding response 99.8 percent of the time. Magazine also comes with a polymer base plate. 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.