Sectioon 5-9 of the 211 user manual states "DO NOT use Argon/Mixed gas regulator/flowmeter with CO2 shielding gas". However, the regulator connection diagram on the same page as the warning shows an optional connection of an Argon/CO2 regulator (supplied) with a CO2 adapter on a CO2 tank; an actual CO2 regulator would not require an adapter. This diagram is very misleading since the use of an Argon/CO2 regulator on 100% CO2 is not supposed to be acceptable. It is my understanding that the supplied regulator with the 211 is for 100% Argon and Argon/CO2 mix and NOT for 100% CO2.