Rubber
O-Ring are one of the most common types of seals because they are inexpensive, easy to make, reliable, and have simple mounting requirements. Furthermore, O-rings are one of the simplest, yet most engineered, precise, and useful seal designs ever developed. They are one of the most common and important elements of machine design.
An O-ring is a round mechanical gasket designed to be seated in a groove and compressed during assembly between two or more parts, creating a seal at the interface. O-rings may be used in static applications or in dynamic applications where there is relative motion between the parts and the O-ring. Dynamic examples include rotating pump shafts and hydraulic cylinder pistons.
O-rings are available in various metric and inch standard sizes. Sizes are specified by the inside diameter (I.D.) and the cross section (C/S) diameter, or thickness. If the size you need is not a standard AS568 or Metric size, you will need either a Vulcanized O-Ring, or a Custom Molded O-Ring.
China [CN] 
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