Feature: 1. 4 In 1 Out: Stereo 4 way sound input mixed into a stereo output, can directly drive headphones or power amplifiers. Maximum drive current of 70mA, can easily drive a variety of headphones and external amplifiers. 2. Simple Control: Each channel has independent volume control, separate input plugs and a single output for the amplifier. 3.5mm headphone jack, potentiometers control each channel volume separately and do not affect each other. 3. User Friendly Design: The modern design of the 4 way stereo sound mixer board looks great on any desktop, and the large controls are easy to use to avoid getting caught on wires, clothing, etc. 4. Versatile: Sound mixer collects sound from many different sources (microphone, guitar, bass and keyboard) into one listening place for monitoring or routing. The power supply is DC 5V‑12V and the amplification is about 2x. 5. Application: Multi input sound mixer is ideal for multi keyboard rigs and recordings where several channels need to be mixed into one track. It's perfect for your keyboards, small stage setups, drum kits, or mixing before going into the main mixer. Specification: Item Type: 4 Way Stereo Sound Mixer Board Material: PCB Size: Approx. 99 x 40 x 16mm/3.9 x 1.6 x 0.6in Sound Interface: 3.5mm Power Interface: 5.5x2.1mm DC Interface Voltage: DC5V-12V Maximum Drive Current: 70mA. Package List: 1 x 4 Way Stereo Sound Mixer Board4 x Black Buttons1 x Red Buttons1 x Sound Cable Note: Please allow some errors due to manual measurement.