Just For Hair Color targets only the gray hair. Replaces it with subtle tones that match your own natural color in 5 easy minutes. The ammonia-free formula lasts up to 6 weeks, until the gray grows out. Just For Men replaces gray with subtle tones in 5 minutes. And, it's as easy as shampooing. Just For Men is good to your hair. It has no harsh ammonia. Special conditioners help protect hair while you color. It's a unique complex of Vitamin E, protein, chamomile and aloe for thicker, healthier looking hair that's easier to control.