This Replacement filter cartridge can serve as the replacement for Filbur# FC-1320, Pleatco# PJW50 and Unicel# C-5300. The technical specifications of the respective replacement filter cartridge is in compliance with OEM# C5300. The top of the replacement cartridge is closed with a w/ string loop and on the other end there is an open hole of 2 1/8 inch. The product is 5 11/16 inch wide and 10 3/8 inch long. This highly reliable product of pool filters can be used in 50 square feet jacuzzi Whirlpool Bath (front load), clear water spas, spillway spas, seven seas spas and Florida Whirlpool.