5 micron 4" x 20" sediment filter cartridge removes sand, grit, precipitated mineral particles, insoluble iron oxide and other debris. Two 5 micron 4" x 20" carbon block filter cartridges strips out pesticides, industrial chemicals, gasoline and volatile organic compounds (VOCs), adsorbs chlorine disinfectants, which are responsible for offensive tastes and odor problems in drinking water. Pre-filter set for WECO LOTUS commercial reverse osmosis water purification systems. Compatible with all standard 4" x 20" Big Blue housing filter systems.