O-Ring No Metal Detectable No X-Ray Detectable System of Measurement Metric Cross Section Shape Round O-Ring Material Viton Durometer (Hardness) Rating Medium Hard Nominal Inside Dia 18 mm Nominal Width 2 mm Actual Inside Dia 18 mm Actual Width 2 mm Color Black Durometer 75 Shore A Meets/Exceeds FKM 75 Nominal Outside Dia 22 mm Actual Outside Dia 22 mm FDA Approved No Package Quantity 25