Amino Acids + B5 is an ultra-thin serum that works with your skin to support its natural hydration barrier. By including a concentrated 17% (by weight) solution of amino acids and amino acid derivatives that mimic your skin’s natural moisturizing factors, this water-based formula keeps the outer layer of your skin protected and well-hydrated without feeling greasy. Plus, it uses 5% (by weight) pro-vitamin B5 to provide surface and below-surface hydration, giving way to softer, smoother skin.