This O-ring is crafted from black Buna-nitrile, featuring a round cross-section and a durometer rating of 70A, making it suitable for a broad range of sealing applications. Buna-nitrile offers high tensile strength along with excellent resistance to abrasion, tearing, and compression set. It operates effectively within a temperature range of -30F (-34C) to 250F (121C) and is compatible with various fluids, including petroleum, HFA, HFB, HFC fluids, vegetable oils, alcohols, acids, and aliphatic hydrocarbons. However, it is sensitive to acetone, ethers, esters, ozone, sunlight, and weathering, so it should not be used in ozone-generating electric motors, welding equipment, or environments exposed to UV light. With a shore durometer of 70A, this Buna O-ring indicates a specific hardness level and its resistance to permanent indentation. A higher durometer value reflects greater resistance to indentation, with the scale ranging from 0 to 100, where 100 means no indentation occurs. O-rings are typically employed to create pressure and fluid seals between overlapping cylindrical surfaces. They are commonly found in applications like engines, faucets, flanges, valves, and various cylinders. Shaped like a doughnut, these circular rings feature a hole in the center. O-rings come in various sizes and can be ordered based on the required nominal inside diameter (ID), outer diameter (OD), and cross-sectional (CS) diameter. These Buna-nitrile O-rings conform to the standards set by Aerospace Standard AS568A, which defines the Aerospace Size Standard for O-rings. Nominal Dimensions: These are the stated or labeled dimensions of a material but do not necessarily represent its true size. They are often rounded for convenience. Actual Dimensions: These are the real, measured sizes of the material, which can be smaller due to processing like planing, finishing, or manufacturing tolerances. Actual ID: 0.676 0.009 Inch (17.17mm 0.23mm) Actual CS: 0.070 0.003 Inch (1.78mm 0.08mm) Actual OD: 0.816 Inch (20.730mm)