The 7.62 mm EX-34 is the smallest member of the The Boeing Company (previously McDonnell Douglas Helicopter Systems and before that Hughes Aircraft Company) family of Chain Guns® and was developed by the company in the 1970s as a private venture, mainly as a coaxial machine gun. It is the standard coaxial machine gun on the British Vickers Defence Systems Challenger 2 MBT and the Alvis Vehicles Warrior infantry combat vehicle used by the British Army. It is also fitted to the export version of the Challenger 2E MBT which as of mid-1999 remained at the prototype stage.