The Zorbi oil scum absorber is one of the most significant advances in hot tub water care in years! The secret is the amazing hi-tech material inside which actually aborbs up to 15 times its weight in oil scum and lotion residues out of the water - without soaking up the water itself. Approx. dimensions are 6.5" long x 3" diameter. Includes tie loop. Replace every 3 to 6 months, depending upon bather load and water quality. Works with all sanitizers.