Inside of the dispenser, a ceramic piezo disc vibrates as electricity passes through. This propels the ultra ?ne TEMPO REFILL particles into the room. The particles are only one micron in size and will stay airborne up to two hours. The TRIPLE S TEMPO AIR CARE SYSTEM uses safer chemical formulations than traditional aerosol sprays, with lower, no added VOCs, no metal cans, refills are recyclable, no isobutane or acetone. Spray intervals may be set from 1 to 60 per hour, allowing more controlled use of the product. Dispenser operates on 3 AA batteries. Choose from four indulgent fragrances that last up to 90 days.