I tried it on a long windshield crack about 12-14 inches

I had a small bulls-eye chip with a radiating spider crack no more than 3/4 inch in diameter.

Not one single inch of the seven inch crack is "invisible" now

Now I have to deal with getting a 12 inch crack fixed in my windshield when I should have just lived with a tiny chip from a rock

a 6+ Inch crack over the next several minutes.

I had a chip in my windshield and this piece of junk made it crack about 5 inches