Features: A re-creation of the classic Ross compressor, with very low noise. Use the Sustain, Attack, and Level knobs to find your ideal tone. Sustain: To control the delaying time of compressing; Attack: To control the starting time of compressing effect; Level: To control the output level. The Attack is especially designed for Bass or high-output active pickup. True bypass design minimizes tone loss. Aluminum alloy casing with stove varnish finish. Powered by a 6FF22 9V battery or 9V DC power adapter (neither included). Specifications: Color: Green Effect pedal size: 11.8 * 6.4 * 3.8cm / 4.6 * 2.5 * 1.5in Effect pedal weight: 300g / 10.6oz Package size: 13 * 7.7 * 6cm / 5.1 * 3.0 * 2.4in Package weight: 330g / 11.6oz Note: Please use the 9V power adapter whose polarity is positive pole outside and negative pole inside. Otherwise, the product may not work properly. Package list: 1 * Effect Pedal 1 * User Manual