This is a self watering “Air Pruning” planter. It goes through water fast because of the open sides. Open sides like this stimulates root branching, leading to a dense root bulb without roots doubling back on themselves. This makes plants becoming “root bound” less of a problem.
This design is parametric, you can resize it for any plant pot. It was designed for 2L pop bottles. I also did a bonsai variant, but I found it dried out too frequintly.