3.5mm male to 2.5mm male, 3-pin TRS cable. Use to connect the G1LRO Universal Radio Controller to HTs through their Speaker Mic connection. It can be used in other places those connectors are used too, but this is the main use case Halibut Electronics is selling it for.
You can get similarly suitable cables elsewhere, or might even have some on-hand already. We offer them for sale here as a convenience, and we make sure the cables we sell are good quality and meet all the requirements.