I use 3.0- Dark Medium Brown.
The box contains 2 applications, real gloves, and even one of those fancy color comb/brushes-- all for about $12.00!
Even the NY Times wrote about it!
The color comes in 3 parts: color, developer, and equalizer. It's packaged like Lik'em-aid, with one large pack sub-divided into 3 bits.
The tricky part is getting all 3 to squoosh out of their separate packets in equal amounts. I strongly recommend using a plastic cup or bowl, emptying the packets, mixing, then applying, as I lack the coordination to use as intended.
There's no noticeable stink while you are using it, just a light, floral-ish scent. I love the low-or-no ammonia formula!!!
The color is good, rich, and not too monochromatic. My hair after using is soft, not processed feeling, shiny. It even works on my very stubborn silver (okay, white. I'm going white, not gray) hairs!