Arizona Sillouhettes makes stainless stoppers with that kind of continuous seal. Most of the others are a chrome finish which can flake off.
I have never used the Arizona stoppers, so I can't speak to their actual sealing capability, but if I do more stoppers I intend to give them a try next to see if I like them better.
Ruth is very nice and helpful, her product is well made, but I've not been fully satisfied with the inconsistent sealing capability.