There is a stereo in the hotel room. What is this?

Humidifier is a household appliance to increase indoor humidity. Humidifier can humidify the designated room, or connect the boiler or central air conditioning system to humidify the whole building. Humidifier industry has developed in China for nearly 20 years. After years of popularization of air quality concept, product development and market cultivation, the function and role of humidifier, a relatively unfamiliar small household appliance, has been gradually accepted by people.