Too thin❓ Too flat ❓ Too sparse-looking ❓ No matter what your eyebrow issues are, RapidBrow® Eyebrow Enhancing Serum can help enhance their appearance. Our applicator brush is specifically designed to make it easier to apply RapidBrow on the sparse-looking areas of your brow line. Youthful, flawless, healthy-looking and absolutely beautiful brows can be yours in as quickly as 60 days.