Features: High sensitivity microphone amplification, ALC automatic level control, amplification of 1000 times. Can amplification weak sounds, directly drive headphones, high sensitivity. It can be used for recording on mobile phones, and the interfaces is all 3.5mm. With excellent interferences resistant performances, with strong connection stability. Build in battery, and can use continuously for 20-30 hours when fully charge. Specifications: Material: Plastic + Metal Color: Black Size: approx. 6.3x5.3x2.2cm/2.48x2.08x0.86inch Input and output port: 3.5mm Phone port: 3.5mm 4-section Microphone gained: 40db/60db switching Ear amplifier power: 105mWx2/16ohms Build in battery capacity: 300mAh Power: DC5V Specification: 3.5x1.35mm Package Includes: 1 Piece Microphone Amplifier 1 Piece Phone Connection Cable 1 Piece USB Charging Cord note: Please allow 1-2cm errors due to manual measurement. Please allow for slight color differences due to different display resolution.