Designed to control and monitor chlorine levels. Use to disinfect water in hot tubs, spas and swimming pools.Each 20g tablet dissolve slowly over a period of time for a steady flow of chlorine in to the water and specifically formulated for the disinfection of Spa, Hot Tub Water and Swimming pools.These 20g tablets are best used in a floating dispenser.Model No. DL51DESIGNED TO MAINTAIN WATER CLEANLINESS & SAFETY - Control and monitor chlorine levels. Use to disinfect water in hot tubs, spas and swimming pools.EASY TO USE - Each 20g tablet dissolve slowly over a period of time for a steady flow of chlorine in to the water and specifically formulated for the disinfection of Spa, Hot Tub Water and Swimming pools.SUITABLE FOR FLOATING DISPENSERS - These 20g tablets are best used in a floating dispenser.