Andoer Caline CP-10 Compressor Guitar Effect Pedal Hot Mushroom Aluminum Alloy Housing Ture Bypass 2 adjustable knobs: level and comp. Mini size, compact and space-saving. Durable jacks and foot switch. True bypass design, minimizes tone loss and get more control of your pedal. Designed with on / off LED, instructs effects status. Powered by a 9V battery or 9V DC power adapter (neither included).