ZEV Technologies Extended Base Pad For Glock, Red Finish, Add +5 Capacity on 9mm, Add +4 Capacity on .40 Cal, Additional Power Spring Included, Glock Magazine Not Included, Fits 17Rd Capacity Glock 9mm & .40 Magazines, Does NOT Work w/10Rd or 15Rd Capacity Magazines BPAD-EXT-GLK-5-R.