CBC-20BB Pentek Replacement Filter Cartridge by Tier1A replacement cartridge for systems that accept 20 x 4. 5 filters, the CBC 20BB WF Tier1 water filter cartridge helps you maintain quality water in your home by capturing particles as small as 0. 5 micron. For three to six months after installation, based on your existing water quality, this cartridge will help to ensure you serve great water while protecting your appliances from the risk of sediment corrosion. Order the CBC 20BB WF Tier1 water filter