Difeel Premium Biotin Hair Oil 2.5 oz - Biotin plays an important role in the health of your hair, skin, and nails. A lack of biotin can lead to hair loss. Difeel pro-growth products are Fortified, strengthening formulas infused with biotin, a water-soluble vitamin that's a part of the vitamin B family. Our pro-growth products are sulfate free, paraben free, phthalate free. They work to keep your hair color vibrant while giving your hair added manageability, softness and shine.