O-Ring No Metal Detectable No X-Ray Detectable System of Measurement Inch Cross Section Shape Round O-Ring Material Buna N Durometer (Hardness) Rating Very Hard Nominal Inside Dia 5/16 in Nominal Width 1/8 in Actual Inside Dia 0.296 in Actual Width 0.139 in Dash Number 203 Color Black Durometer 90 Shore A Meets/Exceeds ASTM D2000 NBR 90 Nominal Outside Dia 9/16 in Actual Outside Dia 0.574 in FDA Approved No Package Quantity 25