This is the replacement filters for iSpring whole house filter systems (fits systems WGB32BM and WGB22BM). This replacement filter pack can be used as the 3rd stage for 20 inch whole house filters. Effectively reduces iron and manganese. It also reduces pipe and water heater damage caused by iron, hydrogen sulfide, and manganese. iSpring iron and manganese reducing filter efficiently reduces iron (max 3. 0 ppm down to 0. 01 ppm) and manganese (max 1. 0 ppm down to 0. 01 ppm). It has higher linear velocities than conventional media delivers high Flow Rates and very low pressure drop; feed water pressure: 20 - 100 psi.