Aqua One Airline Check Valve (2 Pack)
Connect a check (one-way) valve to air line tubing to prevent water back-siphoning down your air line when there is a power outage. Back-siphoning is extremely dangerous and can ruin your air pump, empty your tank, damage your floors and create a shock hazard.
Small and Compact
Fits standard aquarium air line 4mm inner diameter
Allows air to travel in one direction only.
Stops water coming back down the air tube
Easy to install – just cut the airline between the air stone and the air pump and insert check valve into air line