3/16" Thick, Durometer 75?5, -15 to 400°F Viton is a highly corrosion-resistant material used against petroleum fluids, diester lubricants, silicone fluids, phosphate esters, solvents and acids except for fuming nitric acids. It is especially good for hard vacuum services and low gas permeability. Not for use with acetates, ketones, methyl alcohol, brake fluids, hot water or steam.