Pure Essential Oil Works LED Ultrasonic Aroma Diffusers purify the air and generate negative ions through a fine, cool mist to remove pollutants, bacteria, fine dust, smoke and viruses. Helps relieve depression, stress, fatigue and allows for better sleep. Perfect for use in spas, retail areas, home and office. Can be used without aromatherapy oils to add moisture to air. Features auto shut-off when water runs out and quiet operation. Includes AC adapter and water refill cup. One year limited warranty. Essential oils sold separately.