How to Set Up Your HEADROCK: Video of HeadRock: Includes: (1) x headphone amp (1) x Micro USB cable (1) 3.5mm male to male audio jack cable Manual and warranty card Features: Rockville HeadRock Battery Powered Rechargeable Personal Headphone Amplifier 3.5MM headphone output 3.5MM aux input for music player Lithium Battery with 800mAh capacity Rechargable battery lasts 5-8 hours per charge Headphone Amplifier Works with 16 – 300 Ohm Impedance Headphone output power: 65mW@16O 89mW@32O 95mW@64O 69mW@120O 29mW@300O High/Low gain switch Volume control 300mv - 2000mv Strong aluminum case ensures long life and strong heat dissipation Chipset: NE5532 THD: 0.0001% Signal to Noise Ratio: 125dB Frequency Response: ±odB (20Hz-20kHz) AMP Internal Voltage: 8V / 500mA DC power Charging: 5V 1A Weight: 0.17 lbs Dimension (inches): 3.74” x 2.09” x 0.5” ( L X W X H)