How often does an O ring on an underwater camera housing need to be replaced if

clear glass wrote:

Then I thought, why not send an O ring to McMaster-Carr and have them match it?

It might help if I knew what the O ring for the underwatrer housing for the XZ1 is made of.

This one is orange and uses silicone grease; the camera comes with a plastic tool to get it out of the groove without scratching it and the manual warns against stretching it.

Does that indicate the material?

One again, I thank you for your past help and whatever you can tell me.