Additional Details ------------------------------ Product description: An economical 6-pack of 20 x 2.5-inch MatrikX CTO2-20 whole house filter cartridges. MatrikX water filters are the most widely used carbon block devices in the world and provide previously unattainable performance. The dirt-holding capacity and the absence of carbon fines makes the MatrikX CTO2-20 the filter of choice. A superior carbon block combines both high performance and integrity with an exceptional cost-to-performance value. As a result the MatrikX CTO2-20 virtually renders GAC filters obsolete by comparison.