Commercial grade EPDM (Ethylene Propylene Diene Monomer) blended rubber in 60 durometer (a measure of hardness).
EPDM provides superior properties for outdoor and high temperature applications:
• minimum of 1000 PSI tensile strength
• accommodates temperatures from -20 to 230 degree F
• resistant to ozone and many oxidizing chemicals and acids
• highly resistant to sunlight
60 DURO was chosen for toughness but will still have enough softness to create an effective seal.