The MIDI Solutions Quadra Thru is a 1-in 4-out MIDI Thru Box. All MIDI messages appearing at the input are sent to all four Thru outputs. Active circuitry cleans up any skewing of MIDI data bits that has occurred at the input, ensuring reliable operation in setups that require daisy chaining or long cable runs. The Quadra Thru is MIDI-powered, and requires no batteries or power supply to operate with most MIDI products. Used but in great shape.