This WhisperGreen Lite Panasonic bath fan it all. It is extremely, has a motion sensor, High/Low delay timer, Custom Vent versatile Speed Control and SmartFlow Optimum CFM Technology. The motion sensor automatically the fan when somebody enters or exits the room. The versatile speed mechanism the fan to run at a predetermined level of 0 or 50-110 cfm then switches the fan on up to a supreme of 130 cfm when the switch is turned on. The SmartFlow Optimum CFM Technology the cfm at a unswerving level by increasing the speed when needed.