It is a good quality filter cartridge that complies Unicel # C-8341, Pleatco # PMA45-2004-R, Filbur # FC-1007 and OEM # C8341. This 6 ¾ inch long and 8 inch wide filter cartridge has 4 inch hole both at the top as well as the bottom. It can bear the top load of 40 square foot and most suitable for Master Spas Micro Filter. It provides complete protection from dust, sand and worms. Very easy to install this filter cartridge is made of high grade of materials.