Essentially the cards were made from office paper, folded horizontally then vertically to make an A6 sized card. A window was to be cut through the front and inside left pages and an image was to be stuck to the inside right page, so you could see it from the front. Well, these images fit those.
I'm sure you creative types will find other uses for them. Click the pic to go grab them. Password is 'love' (no apostrophes!)