4. O-Ring, No Metal Detectable, No X-Ray Detectable, System of Measurement Inch, Cross Section Shape Round, O-Ring Material Silicone, Durometer (Hardness) Rating Medium Hard, Nominal Inside Dia. Silicone O-Ring, Dash 417 Range -80 Degrees to 450 Degrees F, FDA Approved Yes 3.4 in, Actual Width 0.