The o-ring assortment is made from nitrile rubber, these durable metric O-rings resist oils, hydraulic fluid and water.the o-ring assortment also can be made from silicone and FKM material. Silicones have excellent heat, ozone and corona resistance and have good dielectric stability and resistance to many oils, chemicals and solvents. Silicones possess the best flexible property at low temperature but have low tensile strength and poor wear and tear resistance.