Anyone remember these chocolate bars from the seventies?

They were similar to Milky Way and, if I remember correctly, had a drawing of a mousse in a Superman pose on the front.  I remember when I was about 4 or 5 years old which would have been about 1970/1971 they had several offers whereby if you collected enough wrappers you gave them in at the sweet shop and got a gift.  One was a Spiderman mask made out of plastic similar to a supermarket shopping bag which went completely over your head and I remember my mate and I taking in turns to wear it then chasing each other around the shops - plastic bags for kids to put over their heads certainly wouldn't be allowed these days!!  The other gift was one of those card/paper cracker type things where the paper was folded inside the card and you flicked the thing hard down causing a load cracking sound.

Marvellous!  Oh happy days!!