AC Infinity Cloudline S10, Quiet Inline Duct Fan System with Speed Controller, 10 Inch nm safety co 60Hz Battery Backup 10 Year Sealed 60Hz Battery Backup 10 Year Sealed Lithium Battery Detection Features Smoke Sensor Ionization CO Sensor Electrochemical Audio Alarm 85 dB at 10 feet CO Alarm Levels Activates at: 400 PPM CO (4 15 minutes) 150 PPM CO (10 50 minutes) 70 PPM CO (60 240 minutes) Indicator Lights Constant Green (AC Power) 5 2 Day or Non Programmable Thermostat for conventional or heat pump systems with up to 3 stages of heat and 2 stages of cool with a 3 square inch display this duct fan features an EC motor that is precisely controlled using PWM (Pulse Width Modulation) This gives it a high static pressure rating