This specially designed 0.31" (five-sixteenths inch) Active Aqua Check Valve will safeguard your air pump by preventing nutrient solution from back-siphoning and entering it in the event of a power outage. Simply place the check valve in your run of five-sixteenths inch air line tubing between your air pump and reservoir or hydroponic bucket, and you will never worry about solution returning down the air line and damaging your pump. 

• For pumps that use five-sixteenths inch air tubing
• Compatible with air pump model AAPA45L
• Pack of six check valves