Trrs connector's are not your papas 3.5mm headphone jack (RIP). While maintaining the backwards-compatibility with 3.5mm headphone connectors, they add a 4th lead, this allows your to communicate more data. In the keyboard would we usually used them to communicate between the two half's of our spilt keyboards. But Trrs jacks have seen a lot of other uses including microphone or even video singles and more. When purchasing you will receive 2 SMD trrs connectors.