Supplier for rubber bases for flat bottom 20oz tumblers?

[Chad]

I've just purchased some 20oz flat bottom tumblers but it turns out they don't come with rubber bases, which ideally I'd need to finish off the product. Could someone point me in the right direction please? The supplier told me their standard bottom tumblers come with rubber bases, but the rubber bases don't fit the other style and would need something thicker. I see lots of rubber bases for tumblers online but don't want to fork out for them if they're not going to work.