All I can say is WOW!!! Finally, a product that delivers on its promises. I've fell victim in the past to claims of greatness but this is 100% a winner. I used the glass restoration stain remover to try to bring my badly stained shower screen back to life. As it was a stubborn, thick layer of scum, I left the product on for 20 minutes. It has hardly any odour which is a bonus. I did need to use a slightly "toothier" non scratch scourer but, hey, it worked. Thoroughly and honestly recommend this...