Purchase this item and get 
Water backflow protection for CO2 system
- Prevents the water from flowing back out of the aquarium into the CO2 technology (check valve)
- Very easy to assemble: cut the CO2 hose and insert the backflow protection in between (arrow points towards the aquarium)
- Safety: lock nuts prevent the CO2 hose from slipping off
- For CO2 hoses with Γ 4/6 mm
- Package contents: 1 check valve for CO2 systems incl. hose securing
