Our Pro-Elongating Biotin Lash & Brow Fortifier Serum is designed for those with short, thin, fragile lashes, needing a precise enhancement. It will work to upgrade the look of lashes without the need for false extensions. This lightweight, quick, and easy-to-use serum is packed full of essential ingredients that help boost your lashes' growth, fullness, and length.. The Science. • Biotin aims to thicken hair and stimulate growth.. • Arginine helps strengthen hair, decrease hair breakage and minimise hair loss, and moisturise.. • Hyaluronic Acid works to soak up outside moisture and hold it in, making hair strands more hydrated and healthier.