Marina Airline Plastic Check Valve (1 Pack)
The Marina Check Valve prevents water from siphoning out of the aquarium through the air hose and into the air pump in the event of a power failure or when removing filters and other air-driven accessories from the aquarium.
Small and Compact
Fits standard aquarium air line 4mm inner diameter
Allows air to travel in one direction only.
Protects pumps from water back siphoning
Easy to install – just cut the airline between the air stone and the air pump and insert check valve into air line