The Walther PP series pistols are blowback-operated semi-automatic pistols. They feature an exposed hammer, a double-action trigger mechanism, a single-column magazine, and a fixed barrel which also acts as the guide rod for the recoil spring. The series includes the Walther PP, PPK, PPK/S, and PPK/E. They are manufactured by Carl Walther GmbH Sportwaffen in Germany, Manurhin in France following World War II, and then in the United States by Interarms in Alexandria, Virginia and currently Smith & Wesson. All production has been under license from Walther.