Features: This is a headphones amplifier with build-in battery, supports charging, sound level adjustment and bass adjustment. Can connect the Headphones amplifier to your computer, tablets, mobile phone, game consoles and other devices via 3.5mm cable Aluminum body, support bluetooth-compatible connection, can be used to enhances sound level and sound quality of the headphones. Build-in large capacity battery, support over-charge and overvoltage protections, support highly impedances and low bass resistance Headphones switching. USB C charging interfaces, support 16~600ohm impedances headphones, support a 3 5mm Headphones , a 3 5mm input . Specifications: Material: Aluminum Color: Black Size: about 104.5x63.5x16.5mm/4.11x2.5x0.64inch Input : 3.5mm Earphone: 3.5mm Charging port: USB C Bluetooth-compatible version: BLE5.0 Internal Battery: 3 7V/1400mA Charging: 5V/500mA Operating power consumption: 250mA Endurances working time: >6 hours Signal-to-noise ratio:100db Frequency Response:20hz~20Khz Package Includes: 1x Headphones Amplifier 1x 3.5mm Cable 1x Charging Cord note: Please allow 1-2cm errors due to manual measurement. Please allow for slight color differences due to different display resolution.