[DonRotolo]

The key words in my opinion are "Functionally Equivalent". It doesn't have to have the same structure, just the same function. It can be worn a bit, or cut down from 4" to 2.5", but if it's a conveyer belt and still works (functions) as a conveyer belt, and perhaps is even being used AS a conveyer belt, then it should be OK. You'd use the 4" belt price.

To be certain, ask at Q&A. Just word your question as carefully as possible to address the {r24} issue.