The ZeroWater 5 Stage Advanced Filtration Replacement Water Filters ZR-006 are a pack of 4 white filter cartridges designed for household use. Made of plastic, these cartridges feature a 5-stage filtration system that includes carbon/charcoal, reverse osmosis, and alkaline ionizer methods to provide clean and refreshing water. Compatible with ZeroWater and Aqua Optima systems, these filters are suitable for everyday use in the kitchen and are a convenient way to ensure your water is safe and tasty. Made in Mexico, these cartridges are a reliable option for keeping your water pure and healthy.