20" x 4.5" 5 Micron Carbon Block Water Filter Cartridge with Scale Inhibitor
Amazon.com: Big CTO Carbon Block Water Filters 4.5" x 10" Whole House Cartridges * WELL-MATCHED with CBC Series, WFHDC8001, EP and EPM Series (4 Pack) : Tools & Home Improvement
20 In. Big Blue 5 Micron Carbon Block Whole House Water Filter | Ronaqua