This is a factory 10-round magazine for Glock 21 pistols

These 10-round standard magazines feature a flush-fitting baseplate and numbered witness holes for keeping track of capacity. They’re engineered for optimum fit & function, and designed to drop free when released.

ONLY fits 45 ACP ammunition and Glock 21 pistols.

Glock magazines come with a very strong spring rate from the factory to ensure reliability in the toughest of conditions. Sometimes, magazines are found to be a little bit difficult to load at first. However, after a few times loading and unloading, the springs break in nicely and it becomes much easier to load.