... structure:TC, TB, SC,ect 4.certificate:ISO2001 teflon flat washer describle:1. Material: teflon,NBR, SILICONE, VITON,HNBR, CR, PTFE, EPDM ... , etc. Can choose on your requirement;2. types: TC, TB ... , red, yellow, brown, white, green, violet etc, can make it on your order;6. Apply for: Auto, motorcycle, machinery, water pumps ...