What are these wash out toners that I hear about? Where can I get them?

I read an article at: http://www.blonde-ambition.co.uk/page7.shtml

Its all about maintaining blonde hair. At one point in the article she mentions these colour saving saving, wash out toners that sort of revive your colour in between salon visits. Here’s the important bits of what she says about them:

WASH-IN/OUT TONERS

“I use the little sachets of wella ‘shaders’ or those little triangular boxes of Harmony toners to keep my hair an even shade between root touch-ups. They are my lifesavers in between salon visits. I usually get my roots done and a have ‘long lasting’ semi-put in. When the semi starts to fade I shampoo in half of one of these, lather it up very quickly,( thats all it needs), and rinse. My hair is usually given a new lease of life for about a week after using them”

see the link above for the rest of it. Anyways she is from the UK and I am in Canada. Do we have these here? What brands are they? Where can I get them? How do they work? and are they damaging?

Other info would be nice to, as I am very interested in trying these out! Sorry for the long explanation