I generally have several pairs at hand because I always break 'em. While attending a firearms instructor's conference, I came across the Uvex Genesis which is pretty tough. The frame is flexible so it won't break. Lens meet military ballistic testing for stopping a .177 cal projectile traveling at 650 fps. They're also detachable so if you break 'em, you can replace them for about $10 - a lot cheaper than buying another pair of safety glasses.