2 section air Variable capacitor by Cardwell. 30 pF to 100 pF. Rotor plates 2 3 4 diameter. 12 plates rotor 10 plates stator. Just under 3 16 spacing. Just removed from a homebrew antenna tuner. The knob is stuck on the shaft because the setscrew is broken the end of the shaft between the knob and the bearing is rusty. On one side there is a crack in the stator support insulator but since each stator is mounted with 4 screws the crack does not seem to be a problem.