Viton O-Rings Offer a Wide Spectrum Of Chemical and Temperature-Range Ability. To Be Used With Petroleum Products, Diester Lubricants, Silicone Fluids, Solvents, and Acids (Excluding Fuming Nitric). Viton O-Rings Have a Good Compression Set and Low Gas Permeability. Great For Hard Vacuum Service. Temperature Range Is -30° to 400°F. Hardness Is 70-80 Shore A Durometer. They Are Brown In Color.