Sentinel VCG-27 Variable CO2 Generators 

The Sentinel VCG-27 Variable CO2 Generators gives you several choices for output, from 6 to 27 cubic foot CO2 per hour. 

Available in both Propane and Natural Gas, the VCG-27 Variable CO2 Generators are the safest and most advanced CO2 generators available in today's marketplace.

The VCG-27 Variable CO2 Generator comes standard with 10 pre-installed brass burners. These burners are designed to burn clean and produce consistent blue flames.

Tip-over switch shuts off the gas flow in the event the unit falls or tips over!
Dual redundant low-voltage solenoid valves to add a second layer of safety.
Solid state electronic ignition control module eliminates the need for pilot flame.

Tough powder coated steel enclosure. Two selector valves make setting the CO2 output easy. Comes complete with 10' hose and appropriate pressure regulator. Suggested CO2 level for a grow room is 1500 PPM.

Dimensions: 17.7" high x 15" wide x 10" deep
CO2 tank NOT included.

More info from the Manufacturer (PDF format - Lots of detail.)