"I bought this kit thinking my O ring problems would be solved.
What immediately became clear is that O rings are available in a vastly greater set of sizes than is available in this kit.
It's not only the diameter, but the thickness which is totally crucial.
Based on my experience so far, I'd guess that maybe 20% of the time I need a O ring do I find one which matches. The rest of the time I either need a thicker or a thinner gauge. The kit remains largely unused which is a shame."