In BLACKHAWK s Carbon-Fiber Composite line, they offer single magazine pouches for both 9mm/40 cal. singlestack mags and 9mm/40 cal. double-stack mags. These have a built-in tension spring that keeps your mag secure, but allow rapid removal when you need it. BLACKHAWK s magazine pouches have a built-in tension spring, to hold your magazine in place until you need it and to allow the use of a variety of magazines in each pouch. The most interesting thing about their magazine pouches is that the unique belt clip can be removed, and they can be placed side by side on our Dual Rail Accessory Platform, for those wanting a double magazine pouch, on the same carrier.