Sentinel CO2 Regulator 

The Sentinel CO2 Regulator connects directly to a 20 lb. or 50 lb. CO2 tank to control the flow and amount of CO2 being released. 

The 120 volt solenoid is pre-wired with a 6' power cord to connect to a controller or timer for automated use.

The precision flow-gauge can be set to release between 0.5 and 15 SCFH (Standard Cubic Feet per Hour) of CO2 into your growing area.

This Sentinel CO2 Regulator has an easy to read and understand Color Coded pressure gauge. Maximum inlet pressure 3000 PSI.

The CO2-REG CO2 regulator assembly comes complete with all of the required devices to make using compressed CO2 easy. CO2 tank NOT included.

To couple multiple CO2 tanks together, add a Sentinel CO2 expansion regulator. When you want quality workmanship, choose Sentinel. Carries manufacturer's 3 year warranty.

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