More reliable and easier to use than improvised methods, like taping two magazines together, that can cause malfunctions at critical moments. Closed-top design protects the spare mag from rain, dirt, dust, and debris and prevents the top round from jumping forward under recoil. Independent release system lets you drop the spare mag and the mag in the weapon separately to allow tactical reloads and greater flexibility in clearing malfunctions. Includes Bolt Catch Extension (BCE) that mounts directly to the factory bolt catch and lets you release the bolt, with or without the Redi-Mag attached to the gun, simply by slapping the BCE with an open palm. Installation requires no permanent alterations to receiver or mag well.