Features: Compact and light-weight design, not bigger than a hand of the adults. Built-in distortion effect. Designed with 3 adjuster: Volume, tone, gain. Designed with a clip on the back, easy to fix on belt, pocket or anywhere else. Powered by two AAA 1.5V batteries (not included). Diagram of amplifier: How to connect: Specifications: Instrument jack: 6.35mm mono socket Max.input level: -10dB Input impedance: 1M Ohm Headphone jack: 3.5mm Link jack3.5mm 4-pin socket Link input impedance: 100K Link output impedance: 10K Power: Two 1.5V AAA batteries Product size: 9.8 * 4.7 * 3.5cm / 3.9 * 1.8 * 1.4in Product weight: 56g / 2oz Package size: 12.6 * 7.6 * 3.8cm / 5 * 3 * 1.5in Package weight: 91g / 3.2oz Package List: 1 * Headphone Amplifier 1 * Connecting Cable 1 * Converting Cable 1 * User Manual(English & Chinese)