KollerCraft TOM Aquarium Stellar Air Pump for 40-Gallon to 55-Gallon Aquariums Air pump for aquariums sized 40 to 55 gallons Maintains high oxygen levels while providing optimal water movement to keep fish healthy Dual air port outlets; 1.41 liter-per-minute air volume (per outlet); 2.9 PSI air pressure rating (per outlet) Heavy duty diaphragms deliver years of trouble-free use