This is a built-in battery portable audio amplifier, which supports charging and adjusting volume and bass. Using a 3.5mm cable, it can connect to your PC, smartphone, and game console. It also supports Bluetooth connection. The amplifier has a high and low impedance earphone switch and can support 16-600 Ω impedance earphones. It has a maximum output of 9.9Vp-p and a signal to noise ratio of 100db. The amplifier is made of aluminum alloy and comes with a 3.5mm audio cable, charging cable, and user manual.