The Blue series of Action transfers came in two editions; one had the full 18" background, the other a cut-down 15" background. As you can see from the two covers shown here, both were described as "Big". The 18" had the traditional three-panel structure used previously, whereas the 15" edition was simply a piece of card folded in half.
Picture Credit: the SPLAT Scan Archives, with thanks to StellarX (7 Wonders)
© Tom Vinelott 2021