PENN PLAX Add-A-Stone Air Pump Accessories, 5.5-Inch by 2-Inch Provides a continuous tower of bubbles to help aerate your aquarium Durable plastic can be buried or hidden to add to your dcor Uses a standard 3/16" tubing connection Provides a continuous tower of bubbles to help aerate your aquarium Durable plastic can be buried or hidden to add to your dcor Uses a standard 3/16" tubing connection Provides a continuous tower of bubbles to help aerate your aquarium Durable plastic can be buried or hidden to add to your dcor