Doesn’t come with the set. Sold as 1! This is a recovery serum, Beta-Glucan is ideal for those with impaired barriers or in need of special post-care. Beta-Glucan is a natural polymer derived from Shiitake mushrooms and is known to boost epidermal cell growth while increasing collagen and elastin synthesis. This serum contains high concentrations that help soothe irritated skin, increase moisture levels and reduce erythema. The Beta-Glucan comes directly from the cell walls of the mushrooms. It has the ability to boost the skin's immune system and prevent skin damage, infection and repair irritation of the skin. It will restore moisture and leave skin feeling soft, smooth and firmer.