All USP's use a fiber-reinforced polymer frame stiffened by stainless steel inserts at areas subject to stress and friction. The USP control lever, a combination safety and decocking lever, is frame mounted and quickly accessible, unlike the slide-mounted safeties common on many semi-automatic pistols. The USP recoil reduction system is insensitive to ammunition types and requires no special adjustment or maintenance. The modular design of the USP's internal components allows the control lever function to be switched from the left to the right side of the pistol for left-handed shooters. The USP can also be converted from one type of trigger firing mode to another. Variant 7 is a double action without control lever (no manual safety/decocking lever).