These are the best. They have medical grade rather than food-grade nitrous. I can tell you from personal experience that these are fantastic and leave absolutely no oily residue like "whip-its" and other food-grade brands.
I recommend https://www.amazon.com/iSi-Professional-Whipped-Cream-Chargers/dp/B07LBQT112/ref=mp_s_a_1_3?crid=1C5RDHF540004&keywords=whip+cream+chargers&qid=1555317707&s=gateway&sprefix=whip+cr&sr=8-3 and use a actual whip cream dispenser crackers can freeze to your hand and just not worth it with the dispenser you can take a hit from it or fill a balloon remember to breath in between hits and have fun be safe
Don’t forget to order the charger cartridges, too.