Put 1 to 2 drops on each dryer ball and toss in with the clothes. Use fewer drops of strong oils (peppermint, eucalyptus, lemongrass). Oils can slightly discolor the balls.Safety: let oil soak into the ball before it goes in the dryer and never apply oil to a hot ball or dryer drum (oil is flammable). Essential oils are toxic to cats and other pets; store the bottle out of reach with a child-resistant cap.