The butterfly is powered by a rubber band. Once wound up, the butterfly is placed in a folded piece of card inside an envelope. As soon as an unsuspecting person removes the card, the butterfly flies out creating quite a surprise. Made by Klawvana, England. The company was run by Jack Klaw, who also traded under Novelties Unlimited. This butterfly was one of six designs sold under the name Klawvana Flying Butterflies. I have Philip Treece to thank for permission to include illustrations of the packaging and some other designs from his collection. Philip’s excellent blog www.CollectingMagic.co.uk contains an article on Jack Klaw and his products.