Fredenstein Artistic Comp, FET Compressor 500er Module, OPA2 discrete Audio Operational Amplifier, American made vintage style steel core output transformer, Rotary controls for Input Gain, Release Time, Compression Ratio, Make-up Gain and Wet-Dry Mixing (parallel compression), adjustable Release 70 Ms up to 2,5 Sec., adjustable Attack 0,5, 5 and 25 Ms, adjustable Ratio 2:1 up to 20:1, switchable Side-Chain Filter 150 or 300 Hz, LED Meter, 500 Series Module