Features Reliable Works: With premium aluminum alloy shell, small size and exquisite appearance, elegant and powerful. Microphone Amplifier: High sensitivity, automatic ALC level control, 1000 times amplification, allowing you to hear weak sounds. Practical uses: directly guide the headphones to listen, can be connected to the recording of the mobile phone, and the interface is 3.5mm. Better Designs: This stereo switch box ensures lossless signal and strong anti-interference performance, very reliable. Smart Transportation: Comes with a compact size of 65 x 53 x 25 mm, both storage and transportation are very convenient. Specification: Item Type: Microphone Amplifier Product material: ABS, aluminum alloy Power Supply: DC 5V Interface: approx. 3.5mm/0.14inch Battery: 502030 250mAh lithium battery with built-in battery Package List: 1 x Microphone Amplifier 1 x power cable. 1 x Headphone Cable Package List 1 x Microphone Amplifier 1 x Power Cord 1 x Headphone Cable