High Capacity Mag for all various Glock ..45 Cal Pistols including the 21, and double stack 30's. Mag extends out of the mag well. 26 Round Capacity - Mfg WarrantyPolymer mag body lined with a steel sheath and steel reinforced feed lips. These look and work great. Will lock into all Glock .45 double Stack style mag wells. Does not work with the Glock 36,37 or 38.