In 1982 KO PROPO introduced the Expert EX-1, reported to have been the first to integrate a pistol grip into a transmitter device with a gun trigger to act as the throttle, which later became a popular fixture in radio controlled transmitters.
- "Modellbilens historie". ymr.no.
- "RC10Talk.com – View topic – A comprehensive history of Ko Propo EX1 (1982–2002)". rc10talk.com.
- "Ralph Burch Jr is World Champion". kopropo.com.