Manufactured from good quality natural rubber. Tubing has especially heavy wall which makes it suitable for vacuum use. It is seamless, has good flexing qualities at low temperatures and is acid proof. Tubing also offers high resilience, good tensile strength and tear resistance. Durometer hardness: Shore A, 50. Tensile strength: 2500-3500 psi. Tubing sold in packs of 50 ft. or 10 ft.