and High Quality Color: Blue Qty: 4 pcs You are looking at Z-type foam filters compatible with many models of inflatable hot tubs. Please note, there are many misshapen versions of these filters available at similar prices, such as square or hexagonal shapes. These shapes result from low-cost manufacturing and do not fit as well as round filters, which provide a more consistent surface area. Some are also unusually thick, which can restrict water flow and place added strain on your pump. Round filters are designed to fit properly within the intended housing and deliver better performance. The original filters were used for approximately 12 months and were found to last about one week with difficulty in cleaning. After extensive testing, these foam filters were selected for improved functionality, durability, and cost efficiency. These filters offer better water flow and improved filtration compared to the original models. They are round in shape, ensuring a proper fit and consistent filtration surface. For optimal results, it is recommended to use bromine, as it is odorless, gentle on skin, and compatible with foam filters. If chlorine is used, regular filter replacement is advised. It is normal for these filters to fade in color over time. This does not affect performance and is a natural part of usage. Unlike other sellers who dye foam green to mask discoloration, transparency is prioritized to ensure customer confidence in product quality.