Two chambers, one inside the other. The two are connected with a wick. The top is for plants and the bottom for water. When thirsty, the plants can suck water from the bottom. The water is sufficient for days, even for months. There is no need for watering. So you can forget it totally. The plants are always green and always alive. It is a chance to be with the nature anytime and to escape from the stress in the city.