... or structure:TC, TB, SC,ect 4.certificate:ISO2001 teflon flat washer describle:1. Material: teflon,NBR, SILICONE, VITON,HNBR, CR, PTFE ... , Sealing Gasket.9. Manufacture Process : Heading/washer assembly/Threading/Secondary machine/heat treatment/plating/Anti-slipping/Baking/QA/Package/Shipping telfon flat washer specification ...