Heckler & Koch GmbH (HK) is a German defense manufacturing company that manufactures handguns, rifles, submachine guns, and grenade launchers. The company is located in Oberndorf in the state of Baden-Württemberg, and also has subsidiaries in the United Kingdom, France and the United States.  The company's motto is "Keine Kompromisse!" meaning "No Compromises!"   HK provides firearms for many military, paramilitary units, many other counter-terrorist and hostage rescue teams.  Some of their more notable products include the MP5, UMP submachine guns, the G3, HK417 battle rifles, the HK33, G36, HK416 and MR556A1 assault rifles, the MG5, HK21 General-purpose machine guns, the MP7 personal defense weapon, the USP series of handguns, and the high-precision PSG1 sniper rifle. HK has a history of innovation in firearms, like the use of polymers in weapon designs and an integral rail for flashlights on handguns. HK also developed modern polygonal rifling, noted for its high accuracy, increased muzzle velocity and barrel life. HK has used the operating systems for small arms blowback operation, short-recoil, roller-delayed blowback, gas operation via Short-stroke piston, and gas-delayed blowback.