Pawfly 6 Pcs Aquarium Check Valves One Way Non-Return Air Pump Accessories For Fish Tank Black

Please DO NOT use them with CO2 system. The one way check valves are for common aquarium air pumps. Protect you air pump by preventing aquarium water from back siphoning during a power outage. Detachable design makes it easier for you to clean and repair. Unscrew to open it. Air Hole Diameter: 4mm/ 0.16 Overall Size: 4.3 x 1.5cm/ 1.7 x 0.6(L D) Net weight: 4g. Package Content: 6Pcs Air Check Valve