The Moist-N-Aire Case Humidifier humidifies up to 48 cubic feet, and if your space is larger, another unit may be added. Constructed of stainless steel, a knob on top allows you to select your desired humidity. The reservoir holds 2 quarts of distilled water, and a floating bob indicates when it's time to refill. Paired with a hygrometer, this is the easiest way to keep your cabinet or end-table humidor properly humidified. These are the same units used in many retail store display cases!