Check the listing for details. Chicago Screw Washers Washer Spacer Spacers O ring. Rubber washer washers oring. Condition: New. Listed at 1.91 USD. Rubber washer made from EPDM. These are the type of washer / spacer often used with Chicago Screws in kydex and leather crafts. They are made of high quality EPDM rubber. International Postage.If needed, please contact me for an updated postage rate. EPDM. EPDM rubber (Ethylene Propylene Diene Monomer rubber) is a high-density synthetic rubber primarily used for outdoor applications like rubber roofing. It has dynamic and mechanical properties between natural rubber and synthetic rubber.EPDM rubber is an extremely versatile material that can be used in a variety of applications, from automotive products to HVAC parts. It also acts as a less expensive alternative to silicone and can last for long periods of time with proper use, saving you time and money. Properties Common Name: EPDMASTM D-2000 Classification: CAChemical Definition: Ethylene Propylene Diene MonomerTemperature RangeLow Temperature Usage:-20° to -60° F | -29⁰C to -51⁰CHigh Temperature Usage: Up to 350° F | Up to 177⁰CTensile StrengthTensile Range: 500-2500 P.S.I.Elongation: 600% MaximumDurometer (Hardness)Range: 30-90 Shore AResilience/ Rebound: GoodAbrasion Resistance: GoodTear Resistance: FairCompression Set: GoodAdditional PropertiesAging Weather - Sunlight: ExcellentAdhesion to Metals: Fair to GoodSolvent Resistance: PoorOil Resistance: Poor Benefits & Advantages Resistance to UV exposure, ozone, aging, weathering, and many chemicals - great for outdoor applicationsStability in high and low temperatures - a general purpose EPDM material can be used in an environment where the temperature range is from -20⁰F to +350⁰F (-29⁰C to 177⁰C).Low electrical conductivitySteam and water resistantUsed in the production of extruded rubber or molded rubber productsProperties allow it to be widely used and highly versatile, can be applied successfully in many situationsUsed in the proper environment, the parts will work well and last long without breaking down, becoming brittle, etc. - saving you money on replacementsLess expensive than silicone, with similar properties (where heat below 250⁰F is present)