This FFKM - FFPM O-Ring has a diameter of 304 x 3.5 mm and is Black in color. The hardness of this O-ring 304x3.5 - FFKM - FFPM - F909ZLT - AED - Norsok M710 - Low Temp. (-40°C) - 90 Shore A - Black - ORS178121 is 90. Alternative names for the compound are FFKM – FFPM, and it is commonly produced by Kalrez® | Simriz® | Chemraz® | Perlast® | Isolast® | Parofluor®. The O-Ring is typically used in and has an operating temperature range from -40 ºC to 250 ºC. O-Rings 547518 are referred to as 178121 and have a DIN 3771 size of 304 x 3.5. This item is equivalent to and has an AED - Norsok M710 - Lage Temp. (-40°C) approval. The chemical name of this O-Ring is Perfluorcarbonrubber / Perfluoroelastomeer.