Vacuum Tube Headphone Amplifier with hi-fi sound and Bass Boost function, that turns listening to music into a true audio experience. It has a durable metal body with transparent tube cover, volume control, output power 140mWx2 or 280mW (16 Load) and 12mWx2 or 24mW (300 Load), Headphone impedance of 16 ~ 300 and a frequency response of 10Hz ~ 65kHz. It can be charged via USB or micro USB inputs, has a headphone jack output and two audio inputs. Battery capacity is 16 ~ 18 hours. The package includes a USB cable and audio cable. Dimensions: 120 x 78 x 13,6. Weight: 135 g. Color: Black.