Ultrasonic: There's something to be said about having the right tools for the job at hand, and if you're facing a set of headlights sealed with some nasty permaseal, then the SonicScraper is sent straight from headlight Heaven just for you.
Air Powered: Since it's an air-tool, you will need a compressor with standard quick release to use the thing. Other than that, a strong grip and the willpower to hold on while it goes to work. Some sound blocking earmuffs wouldn't hurt too, because it's really loud.
Bits: The tool kit includes hardened steel blades in two lengths (for shaving permaseal glue off your headlight lens like a boss) and a hardened steel scraping tool that's been specially designed just for the sake of blasting permaseal out of the headlight channel.
Control: The tool features a convenient on-off valve built-into the base so that you can easily cut power when the job is done without the need to disconnect it from your compressor.
Time is Money: Yeah, it's not cheap...but if it saves you several hours of time to open & reseal your headlights (not to mention prevent you from possibly ruining them in the first place) - it's worth it. Especially if you're a pro who does this on the regular.
Notice: This is not designed to cut through plastic, and will do a pretty shitty job if that's your intention. It's sole purpose in life is to help you remove permaseal sealant from the lip and channel between the two halves of your housings.