- Number 4 Jour d automne Mighty Hair Spray repels humidity and keeps your style all day long. Mighty Hair Spray is a strong hold hair spray that provides a flexible hold that will not flake or cause build up. Formulated with Flex-Net Resins, N4 Mighty Hair Spray imparts shine and hold, without giving a stiff, traditional hairspray feeling. It provides UV and thermal protection as well as helping to preserve hair color.