Como Aquarium Fish Tank 2 Pcs Non-return Plastic Air Pump Clear Check Valves

THIS IS A ESSENTIAL IF YOUR AIR PUMP IS LOWER THAN YOUR TANK...EASY TO ATTACH..JUST FOLLOW THE ARROW OR BLOW THRU EACH SIDE TO SEE WHICH END THE AIR IS COMING OUT OF...I USE IT WIT A 5/16 AIR HOSE...NO PROBLEMS HERE