Mercury carb sync tool for bikes with 4 carbs. I sold my bike and don't need this anymore (and the new owner didn't want it). It works great, has all the mercury in it, and comes with 3 additional brass connectors. All the connectors are 3/16" in diameter and they have their rubber o-rings intact. I used it on a Honda V45 but it can be used on any bike that uses that diameter connector, and I'm told you can get other connectors of different diameters.