C Tech Pocket Rock-It S1 Standard Guitar Headphone Amp Instrument Input: 6.3mm male plug T/S Instrument Impedance: 1.0 M ohms CD/Line in: 3.5mm Jack T/R/S Jack T/R/S Headphone/Line out load: 8 Ohms min Battery (Alkaline or rechargeable): 9V Approx. Battery life: 20-24 hours Size: 3.3" x 2.3" x 1.4" Filter Control: 12db Mid/High Adjust Processor: 16 bit Headphones (included): 32 ohm, 44mm driver