I wear Nike Pro Combat Vis-Deflex shorts and they do a decent job. It didn't help much when I randomly ate it on a rail last weekend. I'm still hurting 5 days later.
I plan on buying Forcefield Action Shorts.
Forcefield Action Shorts
If you get the Forcefield, you should get the Action Pro instead of the Action sports. The pro stuff is better, 4 layers (100 joules) and CE2 certified, Sports is only 2 layers