Aerojet is a major rocket an missile propulsion manufacturer based primarily in Sacramento, California with divisions in Redmond, WA; Orange, VA; Gainesville, VA; and Camden, AR. They are the only US propulsion company that provides both solid rocket motors and liquid rocket engines. Their products include a wide range of motors, from main engines used on a number of NASA vehicles and ballistic missiles, down to stationkeeping thrusters for spacecraft. The propulsion devices include rocket motors as large as the EELV Atlas V strap-on rocket boosters. Aerojet provides almost all of the Army's tactical missile rocket motors. They develop and manufacture a wide range of air breathing ramjet and scramjet engines. They also do research in the US in the area of electric ion and Hall effect thrusters. Aerojet is one of only three companies dedicated almost entirely to rocket engines, the others being their rivals at Rocketdyne (liquid rocket engines) and ATK (solid rocket motors).