Big Blue CTO Carbon Block & Sediment 4.5" x 20" Replacement Filter Cartridges 4 Big Blue Filters for a Standard Size 20" Big Blue Housings 2 Sediment (5 Micron) 2 Carbon Block (5 Micron) Standard size filters 4.5x 20 Excellent to remove Sediment, Chlorine, Odors and many other chemicals and contaminants. Effectively eliminates many impurities from tap water to offer sparkling clean and great tasting water throughout your whole house All our filters individually wrapped for freshness and protection while in shipment.