Wow,
Sorry to dig up an old post but I haven't been on the board too much until the past few weeks or so.
Thanks to the OP who posted the images of the W555 advertising piece. It pretty much confirmed the questions/theories that we had about a W555 strip back in this old thread from 2007.
http://www.net54baseball.com/showthread.php?t=86586
Interesting that the players from the W555 strip shown in the 2007 thread aren't shown in the advertisement pictures but I'm sure that they would be found on the reverse side of the large box pictured in the ad.