About the product 1. Mainly used for switching various multi-channel headphone audio signal
2. Which can be used for the same earphone or earplugs to compare different player / headphones
3. 4 3.5mm audio signal input interface, can also be used for output
4. 4 3.5mm audio signal output interface, and can also be used for input
5. Simple installation, plug and play, easy to use