This is an uncommon give-away poster by Sega Pro Magazine.
Sega Pro was a magazine operating in England at the time of Sonic 2, so when they knew the game was coming out, they added a pull-out poster to the issue as a bonus prize. Interestingly, it may be a unique item because where else have you seen this same image? (No where really, yet revealed) It is winter themed. Look at the ground, it's the texture of snow. The 2 is also 'dusted' with snow as Sonic & Tails appear to be leaping/running along side of it while it hovers over the snow. The sky is shown as night time, with stars, but there's a 'haunted' image of strange Eggman up there that's semi-transparent. This was the era where artists weren't sure what the dots on his face were (they are goggles/glasses that are black) if it was all-black eyes, empty eye-holes that look black...or glasses. This one seems to think they're eyes because they are 'angry shaped'.
It's an interesting scene due to the winter theme, and judging by the folds, it's pretty big too. The bottom corner has the magazine's logo.