This scum ball helps to eliminate scum and grime from pool or spa. Its specially patented foam absorbs 43 times its weight in body oils and suntan lotions which improves filtration. Prolongs pool and spa filter life. Float the scum ball in your pool or spa until saturated then clean and reuse. Increases time between cleanings and economical. Lasts up to a swimming season in a pool or three months in a spa. Includes two scum balls per pack.