The CCH2O module lid was designed for ease of use and built to last. Structurally reinforced ribbing provides strength for big trees and a secure fit on the 8 and 13 gallon growth modules. Solid white, non-translucent ABS construction prevents light penetration. Includes an air inlet/finger holes for hoses to easily pass through. Mix and match these lids with multiple plant spacing options for your desired set up.