O-Rings

Made of black Buna-Nitrile rubber (also called Buna-N) for use with a variety of technical fluids.
Durometer (hardness) of 70 for resistance to penetration.
Round cross-section to provide a seal between cylindrical overlapping surfaces.
For use across a wide temperature range from -30 degrees F (-34 degrees C) to 250 degrees F (121 degrees C).