Popular Playthings Interlock Brainteaser Puzzle Challenge yourself with Popular Playthings Interlock, the plug-and-socket puzzle Use blocks from the Interlock set to match the shape shown on the challenge card, without leaving any plugs or sockets showing Includes 12 interlocking puzzle pieces and challenge booklet with instructions and solutions For ages 8 to adult Popular Playthings provides award-winning toys that encourage learning, creativity, social interaction, and good old basic fun