Hikari USA Inc. - Check Valve 2Pk. Aquarium: Water Valves & Bulkheads For use with freshwater or marine aquariums. Eliminates the chance of water siphoning back
The Aquarium Solutions Check Valve for airline tubing. Protects the air pump from back-siphoning. Back siphoning can destroy your air pump or cause an electrical short. Easy to read directional arrow. 2-Pack.