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 20 in Nominal Width 1/4 in Actual Inside Dia 19.955 in Actual Width 0.275 in Dash Number 469 Color Black Durometer 70 Shore A Meets/Exceeds ASTM D2000 NBR 70 Nominal Outside Dia 20 1/2 in Actual Outside Dia 20.505 in FDA Approved No