Wrong! Guys its N20 Get it right. I am an -nitrous junkie, I used to have one 30 pound tank,three 20 pound tanks, one 5 pounder. I got them filled at a filling station where all the guys working there carried guns at all times (see nitrous mafia). Before that I used to 24x24packs with 24 bulbs in each pack from purewhip. and used a gold plated cracker as well as a stainless steel iSi whip dispenser.
Never use a mask of any kind always balloons and youll be cool.
C02 is Carbon Dioxide for bb guns- it is useless.
NO2 is nitrogen dioxide- also useless
N20- Nitrous Oxide -the real deal- a gift of the gods- Comes in large tanks or in those little 24 packs
And it is N... 2... O... So please get is straight. Now excuse me cause I got a Phatty of Headee Medi to inhale out of a punching bag now...

JK