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 3/4 in Nominal Width 1/8 in Actual Inside Dia 5.734 in Actual Width 0.139 in Dash Number 256 Color Black Durometer 90 Shore A Meets/Exceeds ASTM D2000 NBR 90 Nominal Outside Dia 6 in Actual Outside Dia 6.012 in FDA Approved No Package Quantity 2