I was at the flea market on Sunday searching a big pile of junk jewelry and watches. Found a bunch of watch bracelets including an original vintage Casio and Seiko plus several gold topped 40's-50's pieces in decent shape and a ladies Helbros with bracelet. I also did find what I was later to learn is a Bulova Accutron Key Coin. Got the whole lot for $6. Coincidentally I was wearing my 1964 Spaceview. How appropriate. The picture is not mine but mine is just like this. I know they were included in the boxes on early watches but was wondering if there is any definitive dates when they were included and what models etc. I did a search on MyBulova but did not see anything come up on these. The few on Ebay say rare but my question is are they really? Thank you.