I guess they are tempered like most other back glass? One tap on the edge and it will fit in a bucket. I had one saved for the Duster. Kept it in the garage for a couple years - no problem. Went to clean it up for install and bumped an edge. Snap, crackle, pop and nothing left but a pile of glass nuggets. Put the original back in. Now I have another spare sitting outside the garage Anybody need one? It's probably a little better than what's in the car, but not enough for me to bother swapping it.