This is a great little hair protector! I received one with my order of GHDs a few years ago and i'm still using the same bottle! It lasts absolutely ages. You can either spray on whilst hair is damp to reduce damage done whilst blow drying, or you can spray on just before straightening to protect from the straighteners. I have done it both ways and i, personally, prefer to use it before straightening as it gives my hair a lovely shine to it as well as preventing it from getting dry due to the extreme heat. We all know that GHDs are very hot, but most other straighteners are the same heat now so anyone with any other brand of straighteners should use this product too. If i didn't use this product i would have to cut more than an inch off each time i had my hair cut, with this product i can just have a trim as my ends don't get as dry as they used to!