CO2 Regulator

While visiting the hydroponics store I also noticed some used
CO2 style regulators. There were two gauges; one calibrated
in PSI (presume tank side) and the other in CFH. The price
was $40 as is (no guarantees) The lowest graduation is
5 cubic feet per hour. Is this similar to the rating for
the FROG regulator mentioned in the FAQ? Presumably one
would still require a fine control needle valve to get
precise regulation. Is this thing worth the money?

 Steve Pushak - spush at hcsd_hac.com - Vancouver, BC, Canada