Vego Garden's Self Watering Rolling Garden Bed is designed with a heavy-duty rolling frame and an innovative wicking cell system to provide just the right amount of moisture for your plants. The 3.5" tall wicking cell serves as a reservoir, collecting excess water and redistributing it to your plants over time, so you don't have to water as often. It is also designed with air pruning strips so that your plants' roots air prune and don't get oversaturated. This garden bed is perfect for any outdoor space, and convenient to roll inside during harsh weather.