Topps was releasing series in rapid succession. The first series came out in early Spring 1973, the 4th series was probably released sometime in the summer of the same year.
Packs contain two stickers, a checklist, and one piece of gum.
There are 32 different cards, which includes two substitutions (see below for details).
This is the first series where they did not use different backs. All stickers are tan backs.
As in the 2nd and 3rd series, certain titles had to be pulled midway through production. This is the first time, however, that the titles that were pulled were replaced with new titles. The pulled titles are Bum Chex and Choke Wagon, the two replacements are Windhex and Mess Clairoil.
Replacement checklists were produced as well. This was probably done because of how early those stickers needed to be pulled.
Bum Chex and Choke Wagon are fairly tough to find, sometimes selling for over $100. The checklists are not quite as tough however since they pulled the stickers quite a while before they replaced the titles. There are known to be three sheets, the first with Bum Chex and Choke Wagon, the third with Windhex and Mess Clairoil, the one in between has never been found, but may well be a sheet without any of the four titles Bum Chex, Choke Wagon, Mess Clairoil, or Windhex. That would explain the discrepancy between the rarity of the checklists and the rarity of the stickers, but it remains to be proven.
