A gimmick I'm afraid. These balls only work properly when fully immersed in water so that the stones within the ball can dissolve. Most people who will use these balls will most probably have an eco washing machine that uses no where near enough water to allow the balls to be fully immersed. The stones do dissolve, and you can tell this by them getting smaller over time and coming out of the ball and blocking your pump! But the rate of dissolution is nowhere near enough to clean clothes.

A wash that uses no detergent would probably do as good a job as a wash with these balls in.