I was lucky enough to pick this up in the last Beauty Review Vault (Thanks BR Beauties xx) and I used it on my son who kept asking to dye his hair. I thought this would be the best alternative to actually dyeing his hair which I wasn't keen to do as he is only 12.
Silly me didn't read the description where it said it was for blonde or light blonde hair but amazingly enough it showed up on his medium brown hair - quite dark and instead of coming up pastel green, it showed up teal green almost like a beautiful peacock colour.
The spray comes in a standard spray bottle, nothing fancy and user friendly. Being Mr Independent he wanted to do it himself (under supervision of course) and he found it easy to apply. WARNING: Cover everything up in your bathroom especially if it is white like mine as this spray will stain.
It is still in his hair a week after he applied it, a little bit of transfer does come off initially but after a wash, it seems to be fine. Highly recommend if you want to keep the kids from annoying you in the school holidays about colouring their hair.