Dennerle CO2 Softflex Hose provides reliable protection from CO2 leaks. CO2 simply seeps through many hose materials The special Softflex CO2 hose consists of a special CO2-proof plastic to ensure that valuable CO2 arrives where it is needed - in the aquarium. - Special CO2-proof plastic. - Hose diameter 4/6 mm. - Highly flexible easy to install. - Pressure-proof up to 7 bar. 5m length.