Gro Pro® NX Level® Plant Elevators are specially designed to help raise your fabric or plastic pot out of the bottom of a saucer. This elevates the pot out of potential excess water that gathers in the saucers. This can be crucial in preventing root rot, mold issues and helps extend the longevity of your fabric or plastic pot. 13 inch is best used for up to 7 gallon pots, 16 inch is best used for up to 15 gallon pots and 18.5 inch is best used for up to 20 gallon pots.