This was an anniversary present for my wife that I made back before were married. It is fairly simple, just a led circuit. When you put the two necklaces together so the screws touch, the pink necklace(her half) lights up. There is also a hidden message in the back of the pink necklace, engraved into the inside of the grey guitar pick is "I V U"(the "V" actually being a guitar pick) meaning "I pick you." Cheesy I know, but awesome none the less.