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 Medium Hard Nominal Inside Dia 9/16 in Nominal Width 3/16 in Actual Inside Dia 0.537 in Actual Width 0.21 in Dash Number 311 Color Black Durometer 70 Shore A Meets/Exceeds ASTM D2000 SAE J200 Nominal Outside Dia 15/16 in Actual Outside Dia 0.957 in Temp Range -40 Degrees to 250 Degrees F FDA Approved No Package Quantity 50