Unusual construction that don't think I've seen anywhere else. Edges are reeded on the surfaces so they interlock for stacking. The centers are printed paper or plastic. The colored-centers appear to be inserted during manufacture and the chips are transparent so they can be easily read. Three colors: yellow, red, and green.

There are other interlocking plastic adv. chips but most are opaque colors and just hot-stamped on the surface.

I have a pretty extensive collection of advertising chips (started years ago when I saw what the old ones looked like in Dale's book). These three are $5 if someone wants them. I have only the one set of 3 which I think came from an antique shop.