5. O-Ring, No Metal Detectable, No X-Ray Detectable, System of Measurement Inch, Cross Section Shape Round, O-Ring Material Viton, Durometer (Hardness) Rating Medium Hard, Nominal Inside Dia. Brown Viton O-Ring, Dash 251, PK5 Range -15 Degrees to 400 Degrees F, FDA Approved No 5.1 in, Actual Width 0.