3 pack - Hydronix cb-25-2005 carbon block filters are nsf/ansi standard 42 certified for material and structural safety. Cb-25-2005 filters have a particle retention size of 5 microns, and are suitable for drinking water filtration applications. Hydronix cb-25-2005 carbon block filters are manufactured with nsf certified, safe, coconut shell activated carbon to reduce unpleasant taste, odor, chlorine and other contaminants from drinking water. The filter has a 2.5" outside diameter (OD) and an TOTAL length of 20". the operating temperature range is 40 to 180 degrees F, and has a maximum pressure rating of 250 pounds per square inch (psi). this carbon block filter is suitable for use in water dispensing applications where higher chlorine levels are present. Hydronix coconut shell carbon blocks have great cost to performance value, have high chlorine reduction capabilities, great dirt holding performance, and offer exceptional value and performance over other similar filters in the market.