The Oreck AirInstinct 75 HEPA Air Purifier also comes with a timer that allows you to set it to run for one, four or eight hours. Additionally, two different indicator lights remind you when to change filters. Oreck AirInstinct 75 Air Purifier HEPA, Black ABS Plastic: * 3-color lighting system lets you know when it"s working and at what speed * AirInstinct 75 monitors the impurities passing through the sensor * Based on what the APS detects, it turns the air purifier from low, to medium, to high * Captures 99.97 percent of particles (as small as .3 microns) * Washable filters that never need replacing * This odor filter contains an active carbon material to help reduce odors * AirInstinct 75 is ultra-quiet¿¿on the low setting * Timer that lets you set it to run for 1, 4 or 8 hours * AirInstinct 75 automatically switches itself off when the front panel of the purifier is opened * A vented security panel safely covers the fan surface and a specially designed security grill prevents foreign objects from entering the unit * 3-year limited warranty * ENERGY STAR qualified