FlameGlo nesting round mixing bowls, 1974-1976. The color fade alternates, with the top shade matching the bottom shade of the next size bowl. Might sound silly, but I'd prefer they were all like the 402 and this 404.
I have for some time had a suspicion that the FlameGlo 400 bowl set and the mysterious "CRS Red & Orange" 400 bowl set had a connection. It wasn't until I found a collector who had both and could compare them that I was able to see if it might be true.