PROSS for Men Permanent Shampoo-In Color blends away gray hair for natural and healthy looking hair color that lasts up to 6 weeks and provides 100% gray coverage. 3 Minute Hair color-just mix and apply. In 3 short minutes, see and feel the difference! Using PROSS is as easy as shampooing your hair. PROSSís no drip formula is specially designed for the cleanest and easiest at home application. Fade resistant color. Lasts up to 6 weeks. Ammonia free. One kit.