And to make it more confusing, gettin my understanding OEM measures ID and most aftermarket, Gates Malossi etc, measure OD HAHAHA. I tried Gates once on my B&W cus my belt broke and that was all we had at the shop, it SUCKED. Rpm not right, uneven shifting, loss of top speed. When I got a new Kymco Bando i held them side by side and the Gates was much shorter, and almost 2mm thinner!!!! Right AT the service limit lol. It was the belt listed all over the internet for the bet and win 250, also listed in our western powersports catalog. I kept it for a road trip spare, but it'll never go back in by choice. Stick with OEM if you want performance. The only after market belt i use is Malossi, but that's cus I have an overrange in my zuma.