OverviewThis earphone phone amplifier is made of aluminum alloy casing, which is comfortable to handle and has good heat dissipation performance. The appearance is compact and easy to carry, with a 3.5mm input and output interface, suitable for connecting all kinds of smartphone computer equipment. Features: Using aluminum alloy shell, feel comfortable, good heat dissipation.The appearance is small and atmospheric, easy to carry. There is an independent gain control switch. The operational amplifier is suitable for both positive and negative power supplies.With 3.5mm input and output interface, suitable for connection of various types of smartphone computer equipment.Built-in 600mAh rechargeable lithium battery, low power consumption, working time is about 8 hours. Specifications: Input / Output Port: 3.5mm Studio inputLithium Battery Capacity: 600mAh Amplifier Usage Time: 8 hoursWorking Voltage: DC3.7-4.2VCharge Voltage: DC5VSNR: 116dbDistortion: 0.001%Output power: 32 130mWLoad Impedance: 16-300Frequency Range: 20Hz-20kHz(3db)Item Size: 10*6.2*1.5cm / 3.94*2.44*0.59inPackage Size: 13*8*4cm / 5.12*3.15*1.57in Package Weight: 132g / 4.66ozPackage List1 * Headset Amplifier1 * USB Power Cable1 * User ManualNotes: There is a battery inside the machine, please do not open it privately. Please do not use the machine at a high temperature and humidity environment.