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 6 Pack Black One Way Valves The non-return detachable check valves are made of durable plastic and designed to fit most common aquarium air pump while making no noise. Avoid getting water running into your pump when doing water changes or when the power is interrupted. Perfect for aquariums, fish tanks and gardening etc. Note: Don’t place the air valves in CO2 system because the high pressure will make them crack and leak. Fits standard 3/16 inch airline hoses Detachable for easy cleaning An arrow to mark flow direction Good air flow & no restrictions Durable and aging resistant How to
