This FFKM - FFPM O-Ring is 18x2.5mm and in the color Black. The Hardness of this O-ring 18x2.5 - FFKM - FFPM - FDA - USP Class VI - 70 Shore A - Black - Kalrez® 6230 - ORS90766 (Equivilent) is 70 Shore A.The alternative names of the compound are FFPM – Dupont Kalrez and they are mostly produced by Chemraz® - Simriz® - Kalrez® - Spectrum - Triazinico - Isolast® - Parofluor® - Fluorez - Perlast® - HPSealing® - Perfluor® - Polymax. The O-ring is commonly used in and has an operating temperature range from -25 ºC to 270 ºC. O-rings 656907 are indicated as 90766 and have a DIN 3771 Size of 18x2.5. This item is equal to Dupont Kalrez 6230, Freudenberg Simriz 491 and has an FDA 21 CFR 177.2400. USP Class VI. 3A-Sanitary Standard Approval. The chemical name of this Oring is Perfluoroelastomer.