When buying air cushion bb cream, what does it mean to replace it?

The air cushion bb is generally composed of an outer air cushion shell and an air cushion powder in the middle, and the replacement is to add an air cushion powder. You can dig out the air cushion in the middle and replace it with a new one after use, which is equivalent to two air cushions bb.

Extended content

For example, this air cushion bb, in addition to a round bb with a shell, also has a bag, which is a substitute.