I have been using the American flag bottle caps they sell at midwestsupplies for a long time. Yesterday I was at the home brew store in Lawrence and they had them. I bought a package. It said on the package that they were oxygen barrier caps. I never knew that. I got them home and compared them to the ones I have already and they are definitely the same thing. They just are not labeled as such when you buy them form midwestsupplies. Not that I am complaining as I have a stout and a porter that I want to age nearly a year to be ready this winter.
I have always liked these caps, not only for the really cool design, but also because they are a sturdier metal than the other caps I had been using. The home brew store was selling them for $3.75 for a bag of 144. I had been paying $4.99. Shipping is a wash as the home brew store is approx 30 miles away. It makes a nice pleasant get away road trip and there are to excellent breweries in Lawrence.