Primary sealing materials are HNBR (90–95 Duro), FKM (90–95 Duro), AFLAS (90 Duro), and FFKM for extreme HPHT. Each compound is qualified to ISO 23936-2 / NORSOK M710 for RGD and sour service before field release. https://globalsealstech.com/product-category/oil-gas-seals/downhole-completion-tools-seals/