Wide Compatibility--- The mineral purifier stick is suitable for hot tubs up to 1900 liters, suitable for most bathtubs, outdoor pools, hot spring pools, bathtubs, spa pools, plunge pools and much more . Super absorption and purification: The water purifier material has strong absorption capacity and can completely absorb odors and heterochromatic heavy metals and water, eliminating substances harmful to the body such as chloroform and other chlorine in the water. Ensures a healthy and safe environment. Multi-layer filtration: The round filter cartridge filled with mineral material, multi-layer filtration makes the water healthier and can effectively filter limescale, residual chlorine, red worms, rust and more. The purifier can effectively inhibit bacterial regeneration. Safe and high quality: The hot tub purifier is made of high quality ABS and food grade minerals, safe and environmentally friendly, non-toxic and odorless, giving you a healthier life. Lasts 4 months: This hot tub skimmer mineral sanitizer can be used with your hot tub filter system. Please note that it should be replaced every four months.