I have the Covercraft UVS100. Reflective coating on outside, stiff cardboard in middle, felt on inside. Works well, is custom cut for crossfire, folds along pleats and comes with storage bag. Looks much better than the typical soft shield (if the style of the thing matters at all to you). Only downside is cost - it is expensive at $40+.

You can shop for this shield online, just search for it by name.