and High Quality Color: Blue Qty: 4 pcs These are Z-type foam filters compatible with various models of inflatable hot tubs. Please note that similar filters may be available in different shapes, such as square or hexagonal. The round design provides a consistent surface area and a better fit compared to other shapes. Some alternative filters may be excessively thick, which can restrict water flow and increase strain on the pump. Original filters may have limited durability and can be difficult to clean. After extensive testing, these foam filters were selected for improved performance, easier maintenance, and reliable filtration. These round filters offer better water flow and more effective filtration compared to misshapen alternatives. They are designed to fit properly in round filter housings. For optimal results, regular maintenance is recommended. Using bromine as a sanitizer may help extend filter life, as it is gentle on filtration materials. If chlorine is used, frequent filter replacement is advised. It is normal for these filters to experience slight color loss during use. This does not affect performance. The foam is not artificially colored to hide usage effects, ensuring transparency in product appearance.