Biologique Recherche Serum Yall~O2 ensures an optimal hydration level of the skin and lips. Serum Yall~O2 is an intensively plumping and hydrating facial serum that combats dehydration and the effects of aging. Serum Yall~O2 perfectly revitalizes the elasticity of the skin and makes the epidermis smoother and fuller. The skin becomes plumper, looks healthy and feels fresh, your skin will look more youthful.