The RIVAL ARMS RA70G001A Mag Baseplate is compatible with Glock magazines chambered in 9mm Luger, .40 S&W, and .357 Sig, except for models 36, 42, 43, and 48. This baseplate increases weight at the bottom of your magazine, aiding in faster magazine changes and enhancing the firearm's balance. It is CNC machined from aluminum and features a hard anodized finish for durability.