MagPump Magazine Retainer 9mm Double Stack Magazines Ruger AP Black MR-RUGER AP. These Gun Accessories from the trendsetters at MagPump are specifically designed to accommodate double-stack magazines so that you can keep shooting without interruption. With a broader range of pistol calibers on the market today the MagPump Ruger AP 9mm DS Magazine Retainer is a necessary tool for anyone looking to snag some extra rounds. Don't leave the house without the MagPump Ruger AP 9mm Double Stack Auto Magazine Retainer. Specifications for MagPump Ruger AP 9mm Double Stack Magazine Retainer: Manufacturer: MagPump Caliber: 9mm Luger Gun Make: Ruger Gun Model: Ruger American Pistol Country of Origin: USA Package Contents: MagPump Ruger AP 9mm Double Stack Magazine Retainer MagPump MR-RUGER AP : Magazine Retainer 9mm Double Stack Magazines Ruger AP Black