Bubble fulfils two tasks. The modern, refined filter cleans the air by removing dust and germs, while the humidifier at the same time maintains an optimal humidity. The disadvantage of evaporative humidifiers compared to those using ultrasound is the lack of a visual display indicating humidity levels. This appliance, however, has a display that uses bubbles passing through a water tank as indicators. The number of bubbles increases or decreases as the humidity rises or falls. In the rim of the circular display, four different lights indicate the status of the surrounding air. The transparent cover emphasises the clear design of the appliance.