With airflow up to 110 cfm, the SP-LP series is the most powerful low-profile exhaust fan on the market. The SP-LP is powered by an electronically commutated motor (ECM) with Constant CFM adaptive, variable speed technology programmed to overcome the static pressure associated with common residential installation scenarios (0.4 in. wg and above). The motor reacts to increased static pressure by increasing its speed to ensure you have the airflow required to remove unhealthy air and moisture. Optional features include integrated humidity sensor to help control moisure and prevent mold and mildew (SP-LP0511H and SP-LP0511HL) and 2-speed capability for whole-house continuous ventilation (SP-LP0810W and SP-LP0810WL) Lighted and non-lighted models available.