This Pentek FloPlus-20BB carbon block filter cartridge reduces fine sediment, chlorine taste and odor, and protozoan cysts in residential drinking water. It has a nominal (85%) filtration rating of 0.5 micron, and 99.95% efficiency for the reduction of protozoan cysts. It will reduce free available chlorine (FAC) at 2 parts per million (ppm) by at least 90% in up to 50,000 gallons at a flow rate of 4 gallons per minute (gpm). This cartridge is made of modified bonded powdered activated carbon (PAC) filter media that provides efficient cyst reduction with a flow rate and dirt-holding capacity comparable to those of a 10-micron filter. The Santoprene (TPE, thermoplastic elastomer) gaskets seal the cartridge against the housing (sold separately). The cartridge has an initial pressure drop of 4 pounds per square inch (psi) at a flow rate of 4 gallons per minute (gpm), and operates over a temperature range of 40 to 180 degrees F (4.4 to 82.2 degrees C). This carbon block filter cartridge meets National Sanitation Foundation/American National Standards Institute (NSF/ANSI) standard 53 for quality assurance, and is used for purification of residential and commercial drinking water. Specifications Nominal filtration rating 0.5 microns Initial pressure drop at 4 gpm 4 psi Removal of protozoan cysts 99.95% Chlorine reduction capacity 50,000 gallons at 4 gpm Temperature range 40 to 180 degrees F (4.4 to 82.2 degrees C) Maximum dimensions (H x W) 20 x 4-5/8 inches (508 x 118 mm) Cyst reduction certification NSF/ANSI standard 53 The nominal filtration rating is for a particle removal efficiency of 85%. Protozoan cysts include Giardia, Entamoeba, Cryptosporidium, and Toxoplasma. Chlorine reduction capacity is the minimum total amount of water for which the free available chlorine (FAC) at a concentration of 2 ppm is reduced by at least 90%. H is height, the vertical distance from lowest to highest point; W is width, the horizontal distance from left to right; D is depth, the horizontal distance from front to back. Water filters remove undesirable particles, chemicals, and microorganisms from water by means of a semipermeable barrier, adsorption, or biological processes. They are made of densely packed synthetic or natural fibers that trap suspended particles, materials that block microbes or adsorb unwanted chemicals, or substances that cause a chemical change, such as acid neutralization. For most residential, commercial, and industrial applications, water filters are manufactured in the form of replaceable cartridges that fit inside permanent housings. Filtration systems typically consist of a series of two or more types of filters, each designed to remove different contaminants. The performance of filters is measured by the minimum particle size that is blocked, the percentage of particles or microorganisms that are removed, the downstream concentration of unwanted chemicals, the maximum flow rate, and the amount of water that can be filtered before the filter must be replaced. Water filters are used in a wide range of applications, including drinking water purification, swimming pools, industrial processes, and irrigation, among others. Pentair manufactures industrial, commercial, and residential water filtration components and systems. The company, founded in 1966 and headquartered in Minneapolis, MN, meets International Organization for Standardization (ISO) standards 9001 and 14001 for quality assurance.