Feature:1. HIGH SENSITIVITY: Headphone amplifier has high sensitivity, ALC automatic level control, 1000 times amplification, so you can hear the faint sound.2. CLEAR SOUND: Portable headphone amp amplifies your voice with clear, crisp, noiseless, distortion free sound, stylish and powerful.3. INTERFACE IS 3.5MM: Stereo headphone amplifier direct drive headphones to listen, can be connected to cell phone recording, the interface is 3.5mm.4. ALUMINUM ALLOY HOUSING: Microphone amplifier with aluminum housing, compact size, storage and carry are very convenient, beautiful appearance.5. ANTI INTERFERENCE: Headphone amplifier ensures lossless signal as well as strong anti interference performance, very reliable.6. APPLICABLE RANGE: Headphone amplifier is suitable for teaching, trainers, singers, coaches, shopping malls, presentations, outdoor speeches, etc.Specification:Item Type: Headphone AmplifierMaterial: Aluminum AlloyBattery: Lithium Ion Battery 502030 (Built In) Capacity: 250 MAPower Supply: DC 5VInterface: Approx. 3.5mm/0.1inPractical Use: Direct Drive Headphones To Listen, Can Be Connected To Cell Phone RecordingSize: Approx. 65x53x25mm / 2.6x2.1x1.0in.Package List:1 x Microphone Amplifier1 x Power Cord1 x Headphone CableNote:Please allow some error due to manual measurement