This replacement filter cartridge comes with a technical specification of Filbur# FC-3963, Pleatco # PCD50N, Unicel # C-7350, and OEM # 1019401 73532. It is a high performance filter cartridge can handle a top load of 50 Sq. Ft. This state of the art 50 SQ. FT. Caldera Spas (new style), Watkins Mfg.filter with semi-circular handleat the top and2 11/16" at the bottom is of superior quality as per industry standards. It is 10 3/4"long and 7"wide and efficiently provides you dust, sand and worm free clean and clear water solution for your pools and spas. The best in the industry this product matches all your water purifying needs and offers quality with cleanliness and hygiene par excellence.