Fits P228 and older P229 pistols with flat-sided narrow magazine; Not for use in P229 E2 pistols with wider tapered P229-1 magazine; Increased 15-round capacity in a flush-fit design. Features US Patent# 5,386,657 which provides two additional rounds without increasing magazine dimensions; Carbon Steel Tube, heat-treated for strength; Higher tensile music wire spring; Polymer follower and butt-plate; Blued Finish