I used the Graphene ceramic spray bottle, not the concentrated little one. They said it’s good for about 6 months but I’ve seen several online comparisons showing it holds up for about a year. I figured if I missed it up bad or it sucked then I was only out $30 and could have a pro fix it, whereas if I messed up something that lasts 7 years it might be harder/more expensive to undo. You’ll also need to make sure surface is prepped well and as clean and dry as you can possibly get it, and you’ll need good lighting to see it well.