This FFKM - FFPM O-Ring is 421 x 3.5mm and in the color Black. The Hardness of this O-ring 421x3,5 - FFKM - FFPM - Kalrez 4079 - 75 Shore A - Black - ORS180544 (Equavilent) is 75 Shore A.The alternative names of the compound are FFPM – Dupont Kalrez and they are mostly produced by Kalrez® - Simriz® - Chemraz® - Spectrum® - Triazinico® - Isolast® - Parofluor® - Fluorez® - Perlast® - Perfluor®. The O-ring is commonly used in and has an operating temperature range from -15 ºC to 330 ºC. O-rings 578290 are indicated as 180544 and have a DIN 3771 Size of 421 x 3.5. This item is equal to Dupont Kalrez 4079, Greene Tweed Chemraz 615 & Chemraz 551, PPE Perlast G75B, Trelleborg Isolast J8325 & Isolast J9876 and has an General Purpose (+330ºC) Approval. The chemical name of this Oring is Perfluoroelastomer.