For use with airline from an air pump or CO2 system. When placed along the airline between the pump and the aquarium’s air stone or sponge filter it prevents water from backing up down the pipe. This is a more prevalent risk in systems in which the pump is sat below the water level of the tank such as in a cabinet or stand. If the pump were to fail in such an instance without a non-return valve, water would be syphoned from the aquarium.
An absolute must-have for airline use.