Wool Dryer Balls will not cause any damage to your dryer. They are safe to use and actually improve the efficiency of the machine by reducing dry times and preventing static. Dryer balls should be used in smaller laundry loads, which means you are less likely to overload your dryer when using them. Overloading your dryer is a common cause of motor failure and other dryer issues. Wool Dryer Balls are also super soft so they won’t damage the drum of your dryer.