Aquatic Micro Ball Valves are used for regulating air flow through standard tubing for air controlled devices such as air stones; filters; protein skimmers; and ornaments. They can also be used for controlling low pressure liquid feed lines for metering pumps and drip irrigation of water gardens and palaudariums. br> These gang valves fit standard 3/16 in. Airline Tubing. For more information on aquarium aeration; please see our article on Air Pumps.