MagPump Magazine Retainer 9mm Double Stack Magazines CZ Black MR-CZ. Experience the simplicity and versatility of the original mag pump for 9mm semi-automatic pistols with double-stack magazines. These magazine loaders deliver the same proven performance of MagPump magazine loaders but in double stack form. You can purchase these MagPump mag loader accessories as a set of six adaptable retainers or as individual items. However you cannot use the MagPump magazine loader without purchasing the MagPump mag adapter in order for it to work with your magazines. For this reason purchasing the MagPump magazine loader retainers is a necessity rather than an option. Magazine loaders greatly improve your loading speed but they do nothing to help prevent backing out of magazines during use. For this reason MagPump developed a patent-pending retention device that you should install on all CZ magazines loaded with CZ magazine types. The purpose of the MagPump mag loader is to deliver the highest possible fill level of CZ magazines loaded with CZ magazines. Specifications for MagPump CZ 9mm Double Stack Magazine Retainer: Manufacturer: MagPump Caliber: 9mm Luger Gun Make: CZ Country of Origin: USA Package Contents: MagPump CZ 9mm Double Stack Magazine Retainer MagPump MR-CZ : Magazine Retainer 9mm Double Stack Magazines CZ Black