Betta Air stones create a wall of air bubbles to decorate, aerate and improve circulation in your aquarium. To install, connect to standard (4/6mm) silicone or plastic air line from the air pump and lay anywhere in the aquarium. The stone can be hidden from view using rocks, plants, or other decor etc. Betta 1" Air stones are also suitable for use with under-gravel filters. Recommended for use with Betta Airline Tubing, made from either silicone or plastic. 2 air stones per card.