FFKM (perfluoroelastomer) seals handle extreme conditions beyond FKM, up to 300°C and nearly all chemicals. Kalrez or Tecnoflon grades seal oilfield steam injection tools. Infinite shelf life resists degradation. Costly but vital for zero-downtime critical paths. API Monogrammed for wellheads. Compression set https://globalsealstech.com/hydraulic-seals/