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 15 1/2 in Nominal Width 1/4 in Actual Inside Dia 15.475 in Actual Width 0.275 in Dash Number 460 Color Black Durometer 90 Shore A Meets/Exceeds ASTM D2000 NBR 90 Nominal Outside Dia 16 in Actual Outside Dia 16.025 in FDA Approved No