The FloraFlex? Matrix Pad is part of the Matrix System, a patent-pending first-of-its-kind Top Feeding Wicking System that provides the most even way to deliver water and nutrients to your plants. It can be used with pots ranging from 7.5-18 in diameters. You will need a Matrix unit, same size Matrix Pad, and the correlating Matrix Circulator. Water and nutrients travel into the Circulator, hit the slope of the Matrix and are pushed outward into eight maze sections that have individual holes dripping the water and nutrients onto the Matrix Wicking Pad. The Matrix Pad is a lightweight Non-Woven Capillary Mat placed between the Matrix and the medium. Traditionally capillary pads are placed underneath plants, however FloraFlex has designed the Matrix Pad to absorb water and wick to the top of the medium, delivering water and nutrients evenly.