JustForMen Easy Comb-IN-Color #RealBlackOur product will not wash out, lasts up to 8 weeks until the grey grows back; The comb applicator helps you apply all over or on targeted areasUnlike other dyes, our easy, no-mix formula stops coloring after ten minutes. Make sure to follow all instructions included in the package, and perform a skin allergy test 48 hours before use