Stormtrooper Sample Cards: These "Sample Cards" (for lack of a better term) are like proof cards in that no figure is attached, but that is where the similarities end. All but the Star Wars 21 back have no hole punch and four rounded corners, whereas standard proofs tend to have the bottom two corners squared and have a hole punch. The hole punch on this Star Wars card is further right than on production cards, and is thin with a perforated bottom, like punches you commonly see on later cardbacks.
Some of these sample cards appear to be on thicker cardstock than both proofs and production backs. It's not entirely known what they were used for, but it's most likely they were so me sort of demonstration product to show what the final product would look like to both Kenner and possibly retail clients. It's also possible that figures could have been attached to some examples for functions such as the annual Toy Fair or photography needs. Sample cards like this tend to be far less common than proof cards, although typical proofs of these particular cardback variations are not known to exist at this time. Note the date 7/11/83 (or 7/4/83) written on the back of the Return of the Jedi card.