This is an Electro Harmonix Bass Clone Chorus pedal on excellent shape.

Optimized for bass guitar, the Electro-Harmonix Bass Clone chorus pedal takes the classic Small Clone chorus and enhances it for your electric bass. The key is its X-over switch, which removes the lowest frequencies from the chorus circuit. That leaves your low fundamental notes full and punchy while glazing them with sweet chorus on top. Use the Bass control to tweak your dry tone without muddying up the chorus — bassists at Sweetwater love using this pedal to add dimension without losing punch and definition. If you want to add the sonic texture only chorus can offer but are worried about messing with your core bass tone, you need the Electro-Harmonix Bass Clone chorus pedal.