BASTENS AA battery powered winder accessory for rubber band propeller propelled airplane and glider kits stop winding the blades by hand ... do it the quick and easy way with this electic powered winder winder includes a counter to prevent pre mature rubber band breaks and for more consistent flight uses two (2) AA batteries (not included) ... lasts for tens of thousands of winds includes a hand strap for easy carrying easy to use and great for small children. A great way to teach numbers !