The Versacarrier is a state of the art device for carrying a spare magazine. Using extra space in the magazine itself for retention, the Versacarrier allows full functionality in a minimalistic design. It installs like a standard round and the magazine retains its original round capacity. It can be worn inside or outside waistband. It has a quick-draw release and adds zero bulk. This model is for single stack 45 ACP magazines. Note: Any .45 caliber Glock WILL NOT work with any Versacarrier.