MAC's Eye Brows Big Boost Fibre Gel makes brows look fuller, thicker, and more defined with one swipe. This formula won't flake and is sweatproof, waterproof, smudge-proof, and fade-proof for up to 24 hours of flawless wear.These colors use a microfiber-filled gel base to add volume to the brows. The small spoolie brush easily applies the colors for a perfectly shaped and set look.