Hao Pro Air Pump Check Valves 4Mm One Way For Aquarium Fish Tank Pump No Backflow Water Prevent Siphon Flood No Noise Fit Line Tube Hose Red Black White Clear Plastic 18Pcs

Description: Material:plastic Color:whitered and black Quantity:18 pcs Size:Pore diameter: 0.16in/4mmoverall size: 2.10.53in/5.41.35cm(LD). They are good air flow.Simple and reliable.Not easy to crack.The check valves prevent water escaping back up the air lines when the pump timer shuts off.They allow airflow through and prevent siphoning.A simple way to protect your air-pumps from backflow.