Standards

I been to a service and they told me that they can't order the v-belt I need because is to cheep.So i decided to change it myself in the parking lot.

I manage to convince my mother to go and buy a v-belt because when I will finish work all the stores will be closed.The spooky thing is that i find the belt in the part catalog and has the specification 9.5X643MM but the one from the reseller that has the same part number but a different size 9.5X650MM. How the hell the same part can has different specifications ? I was thinking that the part number is created specially to avoid this.
I will tell you tomorrow how was working.