Smooth As Silk Xtreme protein treatment for hair works to smooth and help repair extreme damage. It’s all about the protein, and this bottle is packed. protein treatment adds body, shine, and a smooth-as-silk texture. Used by the finest hair care professionals, Shea Butter, Soy Protein, and Macadamia Nut Oil are combined to detangle, moisturize, rejuvenate, and help revive hair’s texture.