Portable Water Bottle Cap USB Humidifier (White). Instantly turn an everyday plastic water bottle into your own fresh air breathing machine with this Portable Water Bottle Cap USB Humidifier. Perfect for use in your car, in your office, at home, or while traveling. Your own personal humidifier assembles quickly and easily, ensuring you can breathe easy without the hassle. Ultra-quiet with an LED Display. Powered by a USB cord (included). 1.3 oz 2" tall 1.75" circ.