Features: Caliber 9 mm Capacity 18 High Cap Fits P.228 and older P.229 pistols with flat-sided narrow magazine Not for use in P.229 E2 pistols with wider tapered P229-1 magazine Increased capacity to 18-rounds with "Plus-3" Adapter Only 5/8" longer than flush-fit magazines Redesigned tube to improve functionality, heat-treated for strength Anti-Friction Coating allows for easy loading and superior anti-corrosion Interlinked internal components