i did google a bit, and finally found my own answer, green= co2 in the old days, but even better, on the bulb it has tiny print on the side, co2...
guess i got 10 co2 bulbs that ill have to use for legit reasons. i didnt pay, they come free... hope the gf likes whipped cream...
EDIT:
iv noticed you can load more than one bulb into a whipper, but how many is safe? just stick to one? if thats so, would it be a bad dea to make a 16g holder/loader for a 8g designed whipper? its a pretty heavy canister, not light at all for its size.
on that note, how much pressure is in a bulb? out of interest.