Permobond® RS-4001 Black Natural Rubber has excellent physical properties, like tensile strength, abrasion resistance, and elongation. As well has good resistance to most inorganic chemicals, with the exception of strong oxidizing agents. Resistance to weather (ozone) and water. RS-4001 is flexible and will expand and contract with thermal variations of the metal substrate. Often used in applications such as Phosphoric Acid for it’s low permeation physical properties.