My new boat has one of these winches installed on starboard side of the mast. I've only used it once and it was a real pain in the ass, but I'm not sure I was using it correctly.
It doesn't have a ratcheting action so you have to first use a winch handle to tighted it, and then lock it from spinning using the pin lock. I'm also not sure what that second smaller groove is for.
What's the point of this? It was very cumbersome to use coming from someone who has only used standard winch and cleat combo on the main halyard. Also it should be noted that the halyard is all wire, there is no line attached.