Radonaway GP fans are high suction low flow fans to be used with tight soil conditions. The GP401 is slightly less aggressive with a max pressure of 3.4"WC. But the energy savings can be substantial if this fan works for you. Power rated at 60-110 watts. Usually used with 3" PVC duct. This could be a good choice with medium to tight soils and where multiple suction points can be used.