Air-O-Swiss Ultrasonic,$135
What: Humidifier for rooms up to 600 square feet.
Units Sold: 728 last month, 217 last week.
Why: “People buy it because they can see the water coming out as mist. They like to see the results,” says senior buyer William Herring. “It uses high-frequency vibration to generate the mist. It’s also the only humidifier on the market with warm or cool options. Some people like to be able to choose.”
Gracious Home
1220 Third Ave., nr. 70th St.; 212-517-6300