This listing is for 20 pieces filters.Premium quality carbon block filters.Applications:Reverse Osmosis applications in residential, food service, aquariums, commercial and industrial.These carbon block filters can be used to replace traditional GAC(Granular Activated Carbon) and PAC(Powdered Activated Carbon) filters in application where high chlorine reduction is needed.Can be used in ACE Hardware, American Plumber, Pentek, Ametek, Culligan, Playmouth Products, US Filter and many other brands of water filter housings that use a standard size 10" water filter cartridge.Features:Class 1 Chlorine, Taste & Odor ReductionMade with Premium Quality Coconut Shell Activated Carbon 5 Micron FiltrationFits all Standard 10" Filter Housings 5,000 Gallon capacity @ 1 PPM Chlorine with 98% chlorine removal at end of cartridge life.Flow rate: 1 GPM Cartridges are individually shrink wrapped.NSF Certified under manufacturer's part # CBC-1010AAC.Manufactured by CA Ware.Made in Taiwan.