Nellie's Lamby Wool Dryerballs are made of 100% pure New Zealand wool. The Dryerballs come in a reusable tin that doubles as a piggy bank, that way you have a place to save the money from using less energy drying. Toss 4 dryerballs into the dryer to reduce drying time, soften fabrics and reduce wrinkles. All without the use of nasty chemicals. Separate natural fabrics from synthetic fabrics to help reduce static.