Built-in high capacity battery Support charging over voltage protection Support 16~600 impedance earphone Support output volume adjustment and bass adjustment Support one 3.5mm headphone port and one 3.5mm input port Type-c port for charging Aluminum alloy material, full of texture This is built-in battery portable HIFI headphone amplifier,which support charging and adjusting volume and bass.Using 3.5mm cable connect it to your PC,smartphone and game console, etc.it used to improve the volume and sound quality of headphones. Input port:3.5mm(TRS) Headphone port:3.5mm(TRS) Charging port:Type-c Built-in battery:3.7V/1400mA Charging voltage:5V/500mA Standby power:12mA Maximum working current:55mA Duration:24 hours 16heaphone power :48mW 32heaphone power:62mW 150heaphone power:30mW 300heaphone power:18mW 600heaphone power:10mW Maximum output -p:8.2Vp-p :0.02% Signal to noise ratio:100db Frequency response:20hz~20Khz talk: 100db Sound balance:0.3db Working environment temperature:-20 to +60 Colour:black Material:Aluminum alloy Package Contents: 1 x HIFI Headphone Amplifier 1 x 3.5mm audio cable 1 x Charging cable Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.