Well looking at the website , all of the passing panels in the test look about the same. One thing they are trying to say is that it is cheaper, That is if you want the gray, if you want the black finish you have to buy the gray and then put the black over that. I mite be reading it wrong ,The gray looks good and if I ever need gray I will try it out. It seams in less you car doulbles and a salt water going vessel , these products work good. Thanks for the heads up, didn't even know there was a rust bullet.