Keep your air pump safe and dry with this specially designed non-return valve. It protects your air pump from backflow by keeping water out of the air tube. Simply install this Air Pump Check Value in your airline tubing beween the air pump and aquarium water to stop water returning down the air line. Use wherever the pump is installed lower than the aquarium and always use with marine aquariums Total weight: 9g Measures approx. 2.08" long, 0.56" diameter. Tip outside diameter: ~0.18"