The Catalinbread Sinkhole is an ethereal modulated reverb guitar pedal that pairs a harmonically rich "hole" reverb with an impossibly deep four-voice chorus and a warm onboard preamp. 
Controls
MIX: Adjusts the wet/dry signal blend from completely clean to full reverb.
MOD: Controls the rate of the four-voice chorus modulation.
VERB: Sets the decay time of the reverberated signal, allowing for near-infinite sustain that can almost freeze your sound in space.
FEEDBACK: A dual-function control that manages chorus depth and feedback intensity to extract comb filtering, pseudo-phasers, and auto-filtering effects.VOL: Adjusts the gain of the warm internal preamp, usable as a clean boost even with the mix turned all the way down.
Specifications & Features
Bypass: Internally switchable between Buffered (default for trailing decay) and True Bypass.
Power Requirements: 9V to 18V DC center-negative power supply, drawing a minimum of 100 mA (running at 18V provides extra headroom against clipping)