Amino Acids + B5 is an ultra-gentle serum that works with your skin to support its natural moisture 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 sub-surface hydration, making way for softer, smoother skin.