2 Pack Hydronix CB-45-2005 (Pentek EP-20BB, Watts WCBCFF20 Comparable) Coconut Shell Carbon Block water filter cartridge measures 4.5" x 20" standard. This filters offers a 5 micron nominal filtration that is ideal for Whole House, Commercial or Industrial Use as well as use in Hydroponics. Fits in any standard Housing or any Housing that uses standard 4.5" x 20" filters. The Hydronix CB-45-2005 reduces fine sediment and chlorine taste and odor (CTO) in residential and commercial drinking water.