Connect 2 devices such as piano , guitar p38 stereo output to your speaker with aux 3.5 mm input.Small compact adapter to suit various needs associated with joining , and recording audio from various devices.can be used to connect 2 wired mics to mixer , amplifier so that both can be synced with 1 input port.useful when mixers , amplifiers have 1 stereo jack port but 2 devices need to be connect.can be used in wide variety of combinations.Y Shaped , splitter , joiner