3 Pair Non-Return Plastic Aquarium Air Pump Check Valves Specially designed Non-Return Valves will protect you air pump by preventing aquarium water from back siphoning during a power outage. Place these Air Pump Check Valves in your airline tubing between your air pump and aquarium water to prevent water returning down the air line. They are made of plastic material for long time use; The Aquarium Valves are important accessories for air pumps. Measuring approx. 1.35" long, 0.7" diameter; Tip outside diameter: ~0.2"; Total Weight: 5g Package Included:3 Pair Aquarium Check Valves