Keep your pool water clear and clean with a Filter Cartridge (Type IV, Type B) by Bestway. This replacement cartridge measures Ø5.6''x10''/14.2cmx25.4cm in and is designed for 2500 gallon per hour filter pumps. They are easy to clean and sift dirt and debris out of your pool with your pump. Bestway recommends replacing them every 2 weeks for best results.