They are a lithium battery, some LED's, packing tape and magnets. You turn them on and throw them are things with iron (signs, art, cars, etc) and the stick in a none damaging way, providing some color to an otherwise drab scene.
The part of me that dislikes these is the part wondering what damage the lithium batteries will do as they decay. I know large lithium batteries, if punctured, encounters water, it will blow up. So, but throwing these around are you really just spreading a bunch of mini-bombs?