This HNBR O-Ring has a diameter of 21.7 x 3.5 mm and is Black in color. The hardness of this O-ring 21.7x3.5 - HNBR - AED / LT55 - 90 Shore A - Black - ORS187206 is 90 Shore A. Alternative names for the compound are Hydrogenated Nitrile Butadiene Rubber, and it is commonly produced by Viton® - Du Pont - 3M - Solvay - Daikin. The O-Ring is typically used in and has an operating temperature range from -25 ºC to 150 ºC. O-Rings 1044708 are referred to as 187206 and have a DIN 3771 size of 21.7 x 3.5. This item is equivalent to and has an LT55 / AED approval. The chemical name of this O-Ring is Hydrogenated nitrile rubber.