I’m surprised that it’s so cheap. If it is really a chemical vapor deposition process as stated at the DFI URL then the windshield must be removed, delivered to the processor, placed into a vacuum chamber, and treated with the silicone chemical vapor. I think that I’d avoid it if it has to be retreated in a CVD chamber any more often that every 5 to 10 years. If you have to pull the glass and pay a few hundred bucks, just get new glass.