O-Ring No Metal Detectable No X-Ray Detectable System of Measurement Inch Cross Section Shape Round O-Ring Material HNBR Durometer (Hardness) Rating Hard Nominal Inside Dia 2 7/8 in Nominal Width 3/16 in Actual Inside Dia 2.8 in Actual Width 0.21 in Dash Number 336 Color Black Durometer 90 Shore A Nominal Outside Dia 3 1/4 in Actual Outside Dia 3.27 in Temp Range -55 to 300 Degrees F FDA Approved No Properties Resistant to Chemicals Resistant to Oils Resistant to Water