Kelly Manufacturing Company is the manufacturer of the R.C. Allen line of instruments. Based in Wichita, Kan., is one of the largest manufacturers of general aviation aircraft instruments in the world. The firm provides various products, such as artificial horizons, directional gyros, turn coordinators, tachs and many more. Within the domain of directional gyros, Kelly Manufacturing Company offers multi-volt directional gyro indicator, RCA11A series vacuum directional gyro, heading bug and autopilot, etc. Additionally, the firm provides tachometers, torque indicators, oil temperature, voltammeter, low voltage indicator and many more.