Made out of white vinyl material. These stickers are weather resistant, water-proof, and will stick strong on most surfaces and materials.
CAN I PUT THEM ON MY CAR? Yes. If you place it on your car, and would like to reposition it, it will come off clean, leaving no messy residue behind. Keep in mind, once the sun bakes it on, it's not going to come off as easy.
I put one on my car and it's still looking bright and clean months later. I checked to see how removable it was after being in the Florida sun (and rain) all this time, and I'm going to need goo-gone and some patience if I want to remove it all the way. The sticker will not be salvageable, but it still looks good, so I'm going to leave it alone.
If it bakes onto a window, one could easy use a razor blade to scrape it off.