Review (2/5): Applies to both the base and ''full'' dye products.  Just doesn't do the job for dark over grey.
After trying all these pre-mix products claiming to do a great job in only 30 or 40 minutes in one application, the conclusion is obvious. NONE of them will give you a good long lasting dark color over grey on a beard. You must use separate henna and indigo and leave it in for longer to get acceptable results. Henna MUST develop over many hours for permanent strong color. The ''base'' product they sell for problems with using the main product only doesn't do anything as far as I can tell. The support was good but everything they suggested just didn't work. I now spend the better part of each Sunday (about 6 hours) with plant ''mud'' caked on my face and there is no comparison. Only the long 2 step process with thick separate henna and indigo coats can give you long lasting dark brown or black over grey head or beard hair.