The Pentair Pentek ChlorPlus 20BB is a 20-inch Big Blue carbon block water filter cartridge designed for whole house chloramine and chlorine taste and odor reduction. It uses advanced bonded powdered activated carbon (PAC) technology to achieve 1 micron nominal filtration, capturing fine sediment while addressing chloramine and chlorine in your water supply. The ChlorPlus 20BB delivers chlorine reduction capacity of over 500,000 gallons at 4 GPM and chloramine reduction capacity of 6,000 gallons at 4 GPM. The solid carbon block construction eliminates the carbon fines and channeling that can occur with granulated carbon filters. Polyolefin inner and outer wraps with polyethylene netting provide structural support, and Santoprene gaskets ensure a proper seal within the housing. This cartridge measures 4.5" x 20" and fits all standard 20-inch Big Blue and heavy-duty filter housings. It is suitable for residential whole house and point-of-entry water treatment systems. Replace every year or when you notice a drop in water pressure or water quality. Operating temperature range is 40-100 degrees F.