Aquacadabra Check Valve/Non-Return Air Pump Valve x5

• 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

Check Valves (one-way valve) are made 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 aquarium, damage your floors and create a shock hazard.