A double action, polymer framed, semi automatic pistol manufactured by Heckler & Koch GmbH of Germany. Availible in .40 Smith & Wesson, 9x19mm Parabellum, and .45 ACP. There are many variants, including: The USP Compact (which, in addition to the three calibers mentioned above, is availible in .357 SIG), the USP Expert, USP Match, and USP Tactical. The USP was also the basis for the Mk23 Mod 0 SOCOM .45 ACP pistol. Many seem to think the only availible USP is the .45 ACP Tactical model, probably due to the fact that they know little or nothing about ANY guns not featured in some game called Counterstrike, if they even know that there are guns that EXIST outside those used in Counterstrike.
The Heckler & Koch USP is a rugged, reliable service pistol very well suited for military and police applications, as well as recreational shooting.