The first stage of the WGB22BM houses a 5-micron CTO coconut shell carbon block filter. Block carbon is more effective than other forms of carbon in that it is finely ground up carbon packed into a solidified block. This means they have a higher density than other types of carbon filters, and are therefore more effective in removing their targeted contaminants. The carbon block filter knocks out bad tastes and odors, removes up to 95% of sediment and chlorine from the water, and is highly effective on organic chemicals (VOCs) like pesticides, herbicides, and industrial chemicals. The second stage of the WGB22BM has an iron and manganese reducing filter – also great for the plethora of heavy metals found in well water sources. The FM25B iron and manganese reducing filter is only included with the WGB22BM (and WGB32BM), as it is not needed for most municipal water supplies that the WGB22B targets. [Whole House Water Filter that Protects Your Family and Household Appliance from Iron, Manganese, and More] Our iron water filter (FM25B) is specially designed for iron & manganese removal, reducing iron (MAX 3.0 ppm) and manganese (MAX 1.0 ppm). It lasts up to 3 times longer than greensand due to the catalytic media not being consumed in the process. The whole house water filter set also removes sediment, chlorine, rust, herbicides, industrial solvents, and various other contaminants. [Whole House Filter with Standard Size] Our water filter set fits standard housings that require 20″ x 4.5″ whole house water filter cartridges, including brand name models. The 20″ x 4.5″ whole house water filter cartridges have a minimum impact on water flow (up to 15 GPM) and require minimum maintenance. [Top-Notch Whole Home Water Filter] The 1st stage carbon block water filter is made of high-quality coconut shell carbon for maximum filtration efficiency and filter life. Both water filters of F4WGB22BM are tested by an independent third-party to meet NSF/ANSI standards. Both water filters have a capacity of 100,000 gal. Of water, enough to supply a family of four with clean water for a full year. We stand behind our products and if you encounter any problems with any of our products please reach out to us immediately. We are happy to help! [Please Note] The whole house water filter cartridges are individually wrapped to ensure freshness. Please unwrap before use. For well/pond water with very high iron/manganese please check out WCFM500K or WCFM400K whole house water filters. Unlike an RO membrane, these whole home water filters don’t reduce Total Dissolved Solids (TDS), and instead keep healthy minerals in your water. If you are interested in a filter that removes TDS, consider our RO systems.