Some Tuono V4 models do not feature the same size hole that you would expect to be on that model. For that reason, if you check your hole size before ordering you are more likely to get the right pin for your bike. The pin sizes are approximately: #25(5/8"), #31(3/4"), and #15A(1-1/16"). Exact pin specs are proprietary information, but this should help to determine which pin is right for your model. If you are not sure, give us a call at 256-533-1977.