Home XtremPro M1 PORTABLE HEADPHONE AMPLIFIER 20HZ-20KHZOVERVIEW Audio Input: 3.5mm stereo jack Volume Control: ALPS Potentiometer Drive ability: 16-150 Ohms(recommend) Battery Capacity: 1400mAH Output Power: 270mW(32 Ohms450mW(16 Ohms) SPECS SPECIFICATION 14*14*3.2cm 0.3kg