A PVC belt rarely fails on price; it fails on a number nobody verified. This guide reads the specification sheet field by field: total thickness, base fabric and tension member, where fabric weight per ply sets breaking strength and elongation; coating compound, plasticiser content and food-contact declarations; hardness quoted with no test method; and the temperature window that shifts effective hardness on a hot line. Cleats, sidewalls and profile height follow, together with splice method and joint efficiency, tolerances and test reports, incoming inspection and batch consistency across repeat orders. Tables list the questions to ask a supplier and the documents to request.