If you buy something via one of our links, we may earn a commission. The Levoit Classic 160 Ultrasonic Cool Mist Humidifier is on sale for $30, a 25% discount from its normal price of $40.

Diffusers that use water, instead of just air and a fan, usually use ultrasonic vibration to create cool mist. A small, vibrating disc underneath the water tank breaks the oil up into teeny ...