Potassium alum, and it does pretty much what the lady says.
I use mine after shaving, cold splash and apply it wet to the face, tidy up and cold rinse then dry and apply smellies of choice.
I also use it as a natural deodorant and it works extremely well for me.
There are those that wont use Alum,,health and safety etc,,but its your choice I guess.
regards, beejay