Caliber 9 mm Capacity 10 rounds Fits newer P.229 and P.229 E2 pistols with wider tapered P229-1 magazine Will not fit in older P.229 pistols with narrow flat-sided magazines Revised dimpled design accepts standard Mec-Gar floorplates, springs, and follower Carbon steel tube, heat-treated for strength High tensile music wire spring Polymer follower and floorplate