I used to use prizms, its discontinued now i think, to be fair its great to dilute a colour, great on its own, you can get clear toners to get the same effect. It makes the hair incredibly shiny and healthy look not to mention glossy obviously! Great add on for the back bar in my opinion, cons are lasts anything between 8-10 washes the most.
I used to use this all the time, but its had a huge comeback recently, and they've changed the formulation so havent bothered, gelee is a good comparision hths xoxo