From the product description on Hake's, when one was up for auction:

Cardboard sign measuring 13x24" made by CPG Products Corp. in 1979 in conjunction w/Kenner Products action figures for the 20th Century Fox film. This sign was for a special offer "Get A Free Boba Fett Action Figure! When You Buy Any Four Star Wars Action Figures. Mail-In Offer." Sign shows images of characters from film that were also made into other action figures. Characters include Hammerhead, Greedo, Power Droid, Walrus Man, R5-D4, Luke Skywalker (X-Wing Pilot), Snaggletooth, Death Star Droid, Sand People, Jawas, Death Squad Commander, Ben (Obi-Wan) Kenobi, Darth Vader, Storm Trooper, Chewbacca, C-3PO, R2-D2, Han Solo, Luke Skywalker, Princess Leia Organa. Image of Boba Fett action figure is in starburst highlight in center of sign. "Boba Fett...A Fearsome Interplanetary Bounty Hunter-A Threat To The Rebel Alliance, Especially Han Solo! A New Character In Star Wars Sequel." Sign has usual display wear and special offer sticker that covers "Rocket Firing" information is clean. Lt. aging/wear w/top to bottom lt. crease on left. Lt. restoration includes several black marker touch ups on card where there were lt. creases or scuffs. Still displays VF.