Roland Micro Cube Bass RX Battery-Powered Bass Combo Amp Bundle with Tuner, Instrument Cable, and Polishing Cloth Stereo power amplifiers and 4 newly developed 4-inch (10cm) speakers 8 COSM amps, 6 digital effects, and chromatic tuner built in Rhythm Guide function for practical rhythm training Stereo AUX input for CD/MP3 player, Phones/Recording out Battery driven (6 x AA, maximum 11-hour continuous use), AC adaptor included