The SF1 is a dual voltage controlled filter (VCF) module designed to be used either as a pair of identical, but separate VCFs, or as a stereo filter.
9 possible output responses are available from the 2 concurrent outputs for each filter/channel. "Link" mode is ideally suited for stereo applications and allows both filter's cutoff, resonance, and cutoff/resonance CV to be simultaneously using the left-hand controls/inputs. The outputs are routed to a CV-controlled panner/crossfader, allowing modulation of the spacial location of each filter.
Features 
 * 9 possible output responses for each filter/channel (HP, LP, and BP both 12dB/oct and 24dB/oct available from L1/R1 out & Notch, All-Pass, and Phaser available from L2/R2 out)
 * Attenuverters with center detent for frequency CV ins
 * Audio ins contain overdrive when turned past center
 * Self-oscillation capability for using as oscillator(s)
 * Voltage-controlled panning output stage which can be modulated into audio frequencies
Specs
- 18HP module size, 25mm Deep
- Power: 120mA +12V / 120mA -12V
Video: https://youtu.be/TS_S9AGgiX8
Product Specs
- Item Number: 36888
- Make: Weston Precision Audio
- Model: SF1
- Condition: Brand New
- Finish: Black
- Categories: keyboards-and-synths ⇒ eurorack
- Function: Dual/Stereo Filter Panning Phase Shifter Resonator
- Made In: United States
- MPN: WPA-10192
- Modular Grid: Eurorack ⓘ ＋
- Dimensions: 18 HP 25 mm deep
- Power: 120 mA +12V 120 mA -12V 0 mA 5V