I think there's basically two kinds that people use - Oracal 8300 and Lamin-x. The Bluebatmobile kit uses Oracal 8300. I believe the Harmanmotive kit uses Lamin-x - can't confirm but I've felt it and it's the same thick stuff like Lamin-x.
Before looking into it more, I had already ordered a Bluebatmobile kit. I later learned you can just buy rolls of the Oracal 8300 film for about 1/10 of the cost that Bluebatmobile charges. Although, sheets of Lamin-x weren't much cheaper than the Harmanmotive kit. Also, I think it's actually better to work with an entire sheet than the pre-cut kits, since you'll have excess material to wrap it over the edges if you remove your lights for the install. I found it easy to cut out the shapes, so you can really stretch the material if you need to and don't have to conform to any preset alignment - just cover the entire light and then cut out any shapes you need.
Anyways, I liked the idea that the Lamin-x is thicker and read it was easier to install, so I ordered some. The two inner lights were easy to install, since they're flat. The two outer lights are a different matter - not only are they curved, but there's a bump right in middle. I ended up with some small bubbles in mine
. I'm going to wait until the summer and see if they go away from the heat, otherwise I plan to redo them.