All USPs use a fiberreinforced polymer frame stiffened by stainless steel inserts at areas subject to stress and friction. HK pioneered this use of polymer materials in the production of handguns more than 30 years ago with the development of the VP70Z and P9S pistols. The USP control lever a combination safety and decocking lever is frame mounted and quickly accessible unlike the slidemounted safeties common on many semiautomatic pistols. Using a modified Browningtype action with a special patented recoil reduction system the USP recoil reduction system reduces recoil effects on pistol components and also lowers the recoil forces felt by the shooter. This same recoil reduction system has been tested and proven in the HK Mark 23 pistol developed for the U.S. Special Operations Command. The USP recoil reduction system is insensitive to ammunition types and requires no special adjustment or maintenance. It functions effectively in all USP models. Variant 1 is a double actionsingle action with SAFE" position. Control lever manual safetydecoking lever on left side of frame."