GOSAFE Mobile Safe Magazine for Glock Handguns prevents unauthorized use of your firearm by blocking the trigger mechanism and locking the slide closed. The Safe Magazine cannot be removed from the firearm when in the safe position. The mag utilizes a unique-to-user, high-security key to unlock for use. Once purchased, you can order additional keys with the unique product code. The Safe Magazines compatible with all holsters and fits the Glock 17 and 19. - Prevents unauthorized use - Blocks the trigger mechanism and locks the slide closed - Mag isn't removable when in locked position