Phil, the belts have numbers either painted or branded into their sides. I finally figured out to go to a industrial supply house and they'll match the #'s and length for much less than the dealer. A spare isn't a bad idea, because if you're like me, it'll kak right in the middle of the job. Got an old, big 31" Sears with a chink engine-13hp @ Princess for less than $300. So far, so good, touch wood (my head).