Tint Lock Serum works to help your eyebrow tint last longer. It uses an invisible, flexible film, that lightly coats the brow hairs to help hold in colour. The powerful cuticle interlock system works alongside the amino acid action to repair, rebuild and strengthen hair structure. It’s ideal if you want to prolong the wear of your tint or have brittle, damaged brow hairs and want to improve the overall health of your brows.