Rubber Hardness is the hardness of the O-Ring which
can be measured with a shore A Durometer gage. Most
O-Rings are 70-75 durometer. If you do not have a gage,
please mail your samples to Flex at 7300 Industrial Park Boulevard,
Mentor, Ohio 44060 so we may measure. To help O-Rings
handle higher pressure, with less extrusion, we recommend
Contoured Backups. Contoured Backups come in a variety of
materials.