The Pentair Pentek EP-20BB is a 20-inch bonded carbon block cartridge for whole-house, point-of-entry filtration. Its bonded powdered activated carbon (PAC) block reduces bad taste and odor along with chlorine taste and odor for fresher water at every tap. A high-porosity design uses more of the carbon before the block loads up, holding a low pressure drop of 2.0 psi at 4 gpm. A polyolefin bilaminate pre-filter wraps the block to trap sediment that typically clogs carbon cartridges, extending useful life. The cartridge carries a nominal 5 micron rating based on 85% or greater particle removal. Measuring 20" x 4.5", the EP-20BB fits all 20-inch Big Blue and other heavy-duty housings and replaces any 20" x 4.5" carbon cartridge. Rated to 180°F, it is tested and certified by NSF International to NSF/ANSI Standard 42 for material requirements and delivers more than 44,000 gallons of chlorine taste and odor reduction at 4 gpm. Replace when taste or odor returns or flow drops.