I wanted to have a gasket on hand  if I need one. I have a couple of watches that have had the battery replaced a time or two, but the gaskets have never been replaced or had fresh sealant put on them. When the silicone sealant arrives I will put a new gasket on them. I did not look at every one but it looks like a random assortment of sizes to me. I am pretty confident there will be the correct size. The price was right. I am not sure about the quality of the rubber. If you want top of the line gaskets I sure you have to pay plenty for them. I think if I am careful in picking the size and putting it in the watch they will do fine.
I gave 4 stars instead of 5 beceause being new to dyi watch repair I cannot be 100% sure of the quality.
Also,1 bonus, the package says 100 pc, not 72.