Refillable, Empty Water Filter Cartridge Universal Big Blue (4.5" D x 10" H) Clear by CuZn Durable Construction Excellent Flow Rate Available Exclusively From CuZn Water & Air Filters Universal Fit for Slimline (2.5"D x 10"H), Big Blue (4.5"D x 10"H) & Big Blue (4.5" x 20"H)