A cream whipper bulb is a gas bulb that contains nitrous oxide. It works as the charger that releases N2O into the dispenser. The N2O-containing charger acts as a whipping agent. When nitrous oxide is injected into thecanister for whipping cream, it produces pressure that can give the cream a foamy texture. You can only use 1-2 charger bulbs for every preparation depending on whipper size and depending on how often you use your whipped cream dispenser, you have to buy the corresponding number of cream charger bulb refills. ISI bulbs are best used only with ISI whippers