This Replacement filter cartridge serves as the replacement of Unicel# C-4999, Pleatco# PRB100 and Filbur# FC-2397. Further, its technical specifications are in respect with OEM# R173436. With 26 11/16 inch length and 4 15/16 inch width, the replacement cartridge has two equal holes of 2 1/8 inch at the top and bottom. The highly reliable cartridge can be used in 100 SQ. FT. Pentair Pool Products, Rainbow Pl RTL/RCF,Coast Spas (Canada), Sonoma Spas, Pentair Pool Products and Baja Spas.