Keep your pool water clean and clear with a Mainstays Pool Filter Cartridge (Type III, Type A/C). This replacement cartridge measures 4.2 in x 8.0 in (10.6 cm x 20.3 cm) and is designed for above-ground pool filter pumps that utilize a Type A/C cartridge (also known as a Type III filter cartridge). Utilizing your above-ground pool pump, these pool filter cartridges help to sift dirt and debris out of your pool while being extremely easy to clean. For the best results and the cleanest pool, Mainstays recommends replacing your filter cartridges every 2 weeks. While these filters are a great tool to use for keeping your pool clean, they do not replace the need for regular chlorine maintenance. With proper upkeep, chlorine maintenance and the use of these Mainstays pool filter cartridges, your pool can last year after year!