The AutoPot AirBase Square fits with the 2.2 gallon or 3.9 gallon pots. Those pots are used in the AutoPot easy2grow system and 1Pot system. The Airbase eliminates the need for a clay pebble, perlite or hydroton drainage layer at the bottom of the pot! This tough ABS plastic base will allow you to pot up your plants and clean up after the run with increased efficiency saving you time and money. It also has a cut out center section that is compatible with the AirDome however, you do not need to use an AirDome with the AirBase. The AirBase can be used on its own.