The Fzone Pro Series are a professional grade regulator for injecting Co2 in home aquaria. As the compressed CO2 gas inside the cylinder is running low pressure, a single stage regulator has a much higher risk of letting off a huge volume of CO2 gas. A Dual Stage construction prevents E.O.T.D. (End Of Tank Dump) allowing you to maintain stable CO2 output & saturation. High precision needle valves & built-in check valves leaves you to relax knowing your livestock is safe