Itty Bitty Midi Committee: An Acid KitWhat it does The skin is an acidic environment, which means it recognizesand lovesacids. So we made a travel size set with three of the acids it loves the most. C Firma Fresh brightens and firms with 15% l ascorbic acid, aka vitamin C; B Hydra replenishes and hydrates with pro vitamin B5 and sodium hyaluronate, a derivative of hyaluronic acid that has a smaller molecular structure (so it penetrates deeper and is highly absorbable); and T. L. C.