I got sent this the other day - it's a pot full of shiny sparkly metallic hair powder. I got copper, perfect for red highlights. It comes with an application brush and you simply brush it on to your hair where you'd like the colour to go, and then seal with some hairspray. The brush comes in a cute retractable case and slides into the lid so you can't lose it - very clever!
It added a gorgeous shimmer to my wild red locks, but even though it was quite noticeable in person it proved almost impossible to photograph! I therefore called upon my understudy, also known as my gorgeous daughter, who is blessed with golden blonde hair - the kind that people pay thousands in a salon to have, but hers is all natural. The copper powder, as you can see, is a lot more visible on her hair: