Founded in Hagerstown, Indiana in 1926, Perfect Circle became the undisputed world leader in piston ring technology and are credited with practically every major innovation in piston ring development to this day being credited to them. Manufacturing became international and played a vital part in air, land and marine transportation during World War II. In addition to piston rings for cars, trucks, aircraft, locomotive, marine and industrial engines, Perfect Circle manufactured valve seals, cam shafts, seals and gaskets, pistons, cylinder sleeves, turbine wheels and blades and specialized electronic laboratory equipment.