Seller shall deliver the material certificates (including but not limitation to material certificate, warranty, factory test report, TSG certificate etc.) as required by buyer upon the delivery. If the material delivered by seller to buyer is valve, the certificate of material regarding chemical composition and physical property (tensile strength, yield strength) of valve (including:disc, lever, base, plug or wheel) shall be delivered to buyer upon the delivery, otherwise it will be deemed as undelivered. For overdue delivery, the overdue delivery regulations shall govern.