Awful!  Don't waste your money
I wish I had read the reviews before buying this.  This product is far from a clay bar, it's more like a silicon block.  I couldn't form it out into a pancake at all.  I tried cutting a piece off with a box cutter and rubbing my windshield with it to get the gunk off the glass where the wiper doesn't pass over.  It left residue on the glass, didn't pick up any dirt.  I had to scrape the rubbery residue with a razor blade to get it to come off.  I didn't want to get whatever it is into my wash mitt.
Rating: 1 stars