If you want to pimp it out, you can use Recommendation
I bought this when I changed the DriveSprocket on my MONKEY125 from 15T to 16T. If you don't plan on going back to 15T, you can process the OEM and you'll be fine, but if you're in the process of setting it up and there's a possibility of going back to 15T, it's a Must-have item.
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