Dryer balls are sets of balls, either wool or spiky plastic, used to help soften fabrics without chemicals in a tumble clothes dryer.
Many companies manufacture wool dryer balls as well, and it is fairly simple to make wool dryer balls from wool yarn by felting it.
Green Lane Products Ltd. registered their most marketed design of spiky plastic balls in 2004 as a blue ball with square spikes and a pink ball with round spikes. Several other designs were registered simultaneously. A recent British High Court action against PMS International and pound shop operator Poundland who marketed a similar product was settled out of court.
Green Lane also own European Community Trade Marks for the names "dryerballs(R)" and "dryer balls(R)"
References
Dryer ball Wikipedia(Text) CC BY-SA