Jammin Pro MINIJAM 30-Watt - Channel Power Amplifier Battery-powered Jamming Pro mini amp, Includes a total of 32 built-in Rhythm with LIVE Drum Recording, OVERDRIVE- with Tone Control AUX IN jack for jamming along to your favorite tunes using your CD/MP3 player, built-in E-string tuner Accurate and Convenient,9V alkaline batteries allow up to 8 hours of playing Headphone jack