The 4 pack Filter Set for Weddell Duo by Palvo is a high-efficiency shower water filtration system designed for showers. Made of durable plastic and featuring a universal connection thread, this set includes replacement cartridges with a manufacturer warranty of 5 years. NSF certified for quality and bacteria resistant, this shower head filter set is suitable for bathroom use in the United States. Perfect for maintaining clean and refreshing water in your shower, this filter set is a practical and reliable choice for improving your showering experience.