The magazine base pads are precision CNC machined from aerospace-grade aluminum, providing the added weight necessary for quick and reliable magazine drops. These mag extensions instantly boost your Glock's capacity by 5 rounds for 9mm and 4 rounds for .40 cal, compatible with Glock models 17, 19x, 22, 34, 35, and 45. Proudly made in the USA with a flawless finish, these Glock magazine extensions offer the simplest and fastest way to increase your magazine capacity, making them the ideal upgrade for your Glock 17, 19x, 22, 34, 35, or 45.