This simple, robust +3 fits BOTH the polymer HK USP 15-round mag, and the polymer HK USP Expert 18-round magazine. When attached to the “Expert” mag, the system fits HK’s “Jet Funnel” magwell, and extends the magazine to the maximum length allowed in USPSA’s “Limited” division. Raises the HK to 21+1 in 9mm – one round more than the HK VP9 or P30L! For the everyday USP driver, our +3 adds valuable capacity without making the mag too big to conceal. It’s particularly good as a second magazine, where the extra height conceals more easily, and the extra basepad depth makes the mag easier to reload and seat firmly. Like so many products these days, most HK mags ship with a “hook front” basepad. The protrusion on the front of these magazines has a bad habit of hooking things – especially other magazines in the mag pouch. Our design does away with that, creating a mag that’s easier to manipulate, easier to seat, and less likely to cause trouble on your belt. (Kit does not include the pistol or magwell shown.) Due to US State Department restrictions, we cannot ship this part internationally.