Since finding a set of these c. 1920s British "Optical Illusion" cigarette cards several months ago, I've been actively looking for more--I think the colors and graphics are fantastic, and what's more fun than optical illusions? On the back of each card is an explanation of each, or in some cases instructions for how to create an illusion according to the diagram on the face of the card, which admittedly in a few cases seems a fairly cumbersome endeavor! In excellent condition, these came in plastic sleeves with slots that fit them exactly, and I will ship them protected in those, though I'd be most inclined to arranged these in a grid, frame them up, and zone out staring at them!
Curiously, the earlier set I had were for Odgen's Cigarettes but were otherwise identical; this set was made for Ringer's Cigarettes (Edwards Ringer & Bigg). These would have been included as freebies inside cigarette packs, which many people diligently collected. This set of 25 cards is the complete Optical Illusions series issued.
Each card measures 2 5/8" x 1 3/18". All in excellent condition, bright and clean and crisp.