The SD-1 Super OverDrive pedal produces the warm, natural distortion of an overdriven tube amplifier while maintaining the subtle nuances of a player's picking technique. This is one of BOSS' more subtle and smooth overdrive pedals, perfect for blues and rock. Compact overdrive pedal with warm, smooth overdriven sounds Unique asymmetric overdrive circuitry for a classic, natural tube amp growl Tone control provides precise adjustment of drive sound