The durometer scale was defined by Albert Shore in the 1920's. He developed a device that could measure the hardness (resistance to permanent indentation) of a material.

There are many types of durometer scales for different kinds of materials, but most of our rubber products, including o-rings, fall under the “Shore A” or “Type A” category. Durometer is often referred to as “duro” for short. On the durometer scale, lower numbers represent a softer rubber. The hardness of the rubber increases as the durometer numbers go up. Our most commonly used durometers are 50 and 60, which are classified as a medium hardness.


Here is a general reference hardness chart to help choose the correct rubber durometer/hardness for your needs:


Material Comparison Examples

40 Durometer Soft pencil eraser
50 Durometer Weather stripping for doors
60 Durometer Auto tire tread
70 Durometer Running shoe sole
80 Durometer Leather belt
90 Durometer Landline phone cord




1335 West 11th Street, Long Beach, CA 90813-2714

Phone: 562-435-2411 | Fax: 562-436-2140

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