Stainless steel is very rust resistant. These bands will not rust with normal use, but salt water or very prolonged water contact can cause corrosion. They are made of .4mm thick 304 grade stainless steel. They are almost identical in thickness and size to the standard bands that jars come with. They look so similar to standard tinplate canning bands that it can be hard to tell them apart. One way to test is that 304 stainless steel is nonmagnetic but steel is magnetic. Another way is to wash them in the dishwasher a few times and see which bands get rusty! They are slightly taller than standard bands, but they have fit on all the jars we have tried.