To assemble, simply put the plastic propellor blade on top of the plastic handle.  Keep one of your hands still, and quickly roll the handle away from your body with your other hand.  The wacky whirlers look like little helicopters when you launch them from your hands!  

This toy makes a great birthday favor, and it can be cleverly used as part of the entertainment at the party, too!

The handle and blade measure about 7" long.