Kalrez O-Ring Features Outstanding Chemical Resistance To Nearly All Classes Of Chemicals Except Fluorinated Solvents. It Has the Resilience and Sealing Force Of an Elastomer With the Chemical Inertness and Thermal Stability of Teflon. Temperature Range Is 0°F To 500°F Continuous Service, 600°F Intermittent Service. Hardness Is 70-80 Shore A Durometer. No Color.