Carhartt is a clothing company. They make bombproof stuff. Their duck canvas material will stop BBs from 5 feet. To test this, all you need is a willing friend, a BB gun, and a pair of carhartts. Closer then five feet, and you are risking having to take a pair of needle-nosed pliers to recover the projectile from a thigh or similar appendage. Construction workers, oil drillers, and other people with outdoor professions also prefer the brand. Carhartt makes coveralls, pants, jackets, and other assorted clothing. Another brand of heavy duty clothing is Filson's.
Some notes on Carhartt clothing construction: Most seams are triple stiched, as opposed to the double stitch found on most Levis or generic jeans. On some pairs, the knees have an extra layer of cloth sewn on the outside from mid thigh, all the way down to the upper calf. These chaps are meant to be used hard. If you see a hole at the bottom of this outer layer, it is supposed to be there. Carhartt makes it there so that when you wear through the first layer, and stuff gets in between the layers, it has a place to fall out. They make heavily insulated pants, jackets, and coveralls. The insulated stuff is lined and stuffed with a polyester filling. This is why they are used all over Alaska. On the company website, there is a story about a guy who's riding lawnmower tipped over onto him. His insulated Carhartt jacket jammed the blade. I would be tempted to believe this, as the pants I have survived many a late night excursion involving many barbed wire fences.