IGS Audio Tube Core 500, Tube Vari Mu Compressor, 500er Series, fully symmetric design - from Input to Output, VU Meter, Frequency response +/-0.2dB: 20Hz-20KHz, Release: 0.1s - 4s, Attack: 10 - 300 ms, max. Gain: 35dB, Input: Carnhill Transformer, Output: Sowter Transformer, Potentiometers for Gain, Out, Attack, Treshold and Release, Dimensions: 500 Series Module