Mr O-Ring 339 Buna/Nitrile O-Ring, 70A Durometer, Black, 3-1/4" ID, 3-5/8" OD, 3/16" Width (Pack of 1) This O-ring is made of black Buna-nitrile, is round in cross-section, has a durometer of 70A, and is designed for use in a wide variety of sealing applications. Buna-nitrile can have high tensile strength, and abrasion, tear, and compression set resistance. It can be used in temperatures between -30 degrees F (-34 degrees C) to 250 degrees F (121 degrees C), and is compatible for use with petroleum, HFA, HFB and HFC fluids, vegetable oil, alcohol, acids and aliphatic hydrocarbons. Buna-nitrile is vulnerable to acetone, ethers, esters, ozone, sunlight and weathering and should therefore not be used in ozone-generating electric motors, welding equipment, or in applications with exposure to UV light. This Buna O-ring has a shore durometer of 70A. Shore durometer is the hardness of a material, and its resistance to permanent indentation. A higher durometer value indicates greater resistance to indentation on a scale of 0 to 100, with 100 indicating no indentation. O-rings commonly provide a pressure and fluid seal between cylindrically shaped, overlapping mating surfaces and are commonly seen in engines, faucets, flanges, valves, and various cylinders. They are circular in shape, with a round cross section, and a hole in the center, similar to a doughnut. O-rings are available in various sizes, and can be ordered based on required nominal inside diameter (ID), outer diameter (OD), and cross-sectional (CS) diameter. These Buna-nitrile O-rings meet standards defined by Aerospace Standard AS568A, which is the Aerospace Size Standard for O-rings. Features Made of Buna-nitrile (also called Buna-N) for use with a variety of fluids and hydrocarbons Temperature Range: -35C (-31F) to 120C (248F); Shelf-life: 15 Years These versatile o-rings perform well in petroleum based oils fuels, aliphatic hydrocarbons, vegetable oils, silicone oils greases, ethylene glycol, dilute acids, and water to below 100C (212F) Durometer (hardness) of 70A for resistance to penetration O-ring Size meets standards defined by AS568A (b) ID (Nominal): 3-1/4 ID (Nominal): 3/16 CS (Nominal): 3-5/8 OD Fast and Free Shipping You're already purchasing the item. Why pay additional for shipping, especially slow shipping? We get your order shipped out within 1-business day and delivered to your doorstep as quickly as possible. Competitive Pricing With our dynamic pricing model, our prices are always competitive. Our prices are some of the lowest that you will find on the internet. Rest assured that you're getting a good deal when purchasing with us. 30-day Money Back Guarantee We are committed to making sure that you leave this transaction satisfied. If you're unhappy with the product for any reason, you may return it back for your money-back or a replacement within 30 days. No questions asked!