No offence, but did you try the Search function?
I just searched '20oz co2' and found the answer within five posts.

search.php?keywords=20oz+co2&terms=all&author=&sc= 1&sf=all&sk=t&sd=d&sr=posts&st=0&ch=300&t=0&submit =Search

(5th post down, posted by Mario (maddox10))