Airbox Refill Cartridge 4 Filter Size:Airbox Refill Cartridge 4 Plus and works with heavy gauge

and works with heavy gauge ABS grow mod trays that will not bow

some of the nutrients will precipitate

The Under Current utilizes negative water pressure to recirculate oxygenated nutrient solution through the plant's root zone ensuring pH and EC levels are uniform throughout the entire system

air blows towards the floor to provide blanket-style airing

Airbox Refill Cartridge 4 Filter Size:Airbox Refill Cartridge 4 Plus and works with heavy gaugeRefill cartridge for Air Box Air Filter Stealth 1 2 3 4 4+, fits these three models. Single Filter. This refill cartridge size is suitable for Airbox 1, Airbox 2 and Airbox 3, Airbox 4, and Airbox 4+. (IMPORTANT: Order 1 OR 2 OR 3 OR 4 OR 4 Plus cartridges as required for your Air Box unit)