Rubber O Rings
An O-ring, also known as a packing rings,
O-rings are available in various metric and inch standard sizes. Sizes are
specified by the inside diameter and the cross section diameter (thickness).
The seal is designed to have a point contact between the O-ring and sealing faces.
This allows a high local stress, able to contain high pressure, without exceeding
the yield stress of the O-ring body. The flexible nature of O-ring materials
accommodates imperfections in the mounting parts.