Just for men shampoo in hair colour jet black is a foolproof haircolour which lets you pinpoint greys as it shuts itself off at just the right colour giving you the perfect jet black results every time it works within 5 minutes and the results last up to 6 weeks easy to use just for men shampoo in hair colours are easy to use simply comb in the dye then the shampoo and notice the difference in just 10 minutes no mixing no mess does not contain ammonia or peroxide as an added bonus ju