These are felted, 100% wool dryer balls that are approximately 3" in diameter. They are durable and, if treated properly, can be used for years. To use, simply place in dryer with wet laundry and run your dry cycle as usual. These balls bounce through the wet clothes and allow the warm air to disperse more evenly between the layers of clothing. This causes drying time to be shortened. For best results, use 2-5 balls per load. Choose from unscented, lavender or vanilla scented dryer balls. Essential oil will be added if you choose the scented option. This scent will last the first few dryer cycles and you can add a few drops of oil to the ball after every couple loads, to keep it lightly scented, if you choose.