Rides In The Storm HFD Discrete Analogue 4 Pole Highpass Filter Module. Powerful HPF with clear and accurate low noise performance. Discrete VC-HPF Powerful HPF with clear and accurate low noise performance. 2/3/4 Pole operation, selfoscillation GAIN for Audio IN Resonance Compensation Resonance Boost for distorted sounds Attenuators for Reso Comp, ENV IN, XFM IN and LFM IN CV IN for Keytrack (1V/Oct) Reso, ENV, EXPonentiell and Linear FM Perfect match with SED-CSM via serial insert or all other VCF modules 4HP Depht: 25mm Power: +/-30mA.