Current Culture 1-Site Multi-Mod Expansion Kit for Under Current XL with One-Site Lids (1 x 8" Net Pot)1 Site Expansion Kit Is Great For Replacing a Single 8 Gallon Growth Module For Your Under Current XL! All Expansion Kits Now Include: Multi Mod Growth Module, Aeration Manifold Fittings, and Air Hose Whips. NOTE: This multi mod expansion kit is designed to be used to expand the new 2019 multi mod under current systems. This expansion kit will NOT work with the classic systems. If you are looking to expand an old classic under current systems, please