“The Germ Guardian™ Digital Ultrasonic Humidifier
(H-3000) uses nano-silver technology to prevent mold and bacteria from growing in the water tank.”

(Source: http://www.guardiantechnologies.com/prod_humiddigi.html)

“The Germ Guardian™ Manual Ultrasonic Humidifier
(H-2000) uses nano-silver technology to prevent mold and bacteria from growing in the water tank.

By humidifying clean water, you provide a healthier breathing environment by not spreading germs and bacteria into the air. The Manual Humidifier has an option for warm or cold humidification. An adjustable spray function helps regulate the volume of spray you desire. And since the humidifier is ultrasonic it's virtually silent when it runs, making it ideal to have on while you sleep. “