Description Features: Headphone mini plug amplifier with distortion effect. With built-in 3.7V 300mAh rechargeable battery, up to 8 hours working-time. Enjoy the music whenever you are at home or outdoors, by simply plugging it into your guitar. Function Knobs: Control tone, distortion, volume adjustment. AUX in jack lets you along with cellphone or MP3 player. 3.5mm jack to your earphone. Specifications: Material: ABS+Electronic Board Weight: 70g Size: 8.1x7.7x2.8cm Note: 1.Please allow 1-2cm errors due to manual measurement, make sure that you do not mind before you order. 2.Due to difference between different monitors, the picture may not reflect the actual color of the item. Package includes: 1x Headphone Amplifier