O-Ring No Metal Detectable No X-Ray Detectable System of Measurement Inch Cross Section Shape Round O-Ring Material EPDM Durometer (Hardness) Rating Medium Hard Nominal Inside Dia 21 in Nominal Width 1/4 in Actual Inside Dia 20.955 in Actual Width 0.275 in Dash Number 470 Color Black Durometer 70 Shore A Meets/Exceeds ASTM D2000 SAE J200 Nominal Outside Dia 21 1/2 in Actual Outside Dia 21.505 in Temp Range -65 Degrees to 300 Degrees F FDA Approved No