The FloraFlex� 7.5-12 in Universal Round FloraCap� is a patent pending revolutionary tool for top feeding that also helps eliminate algae. The FloraCap� is designed to give you a more consistent flow rate, even distribution, increased air flow, and stabilization. Fill the cap with water and nutrients by hand or automate with FloraClips. The FloraCap� strategically covers the top of the media allowing the root zones to dry at a more consistent rate and delivering the necessary oxygen your plants need to thrive. Fits pots from 7.5 to 12 in diameter.