PotHoles Drainage Discs give your Potted plant perfect drainage in one easy step! Hydroponic filler holds moisture for plants while improving oxygen flow, eliminates soil messes by covering drainage hole, no more searching for loose rocks or clay chips and Potholes are reusable -just rinse off and place in your next pot. 8.5" PotHoles are best suitable for use in 12" to 18" pots