I have some less expensive ones which look similar. They were fool proof in Vegas as I fell off several times. Not a scratch. The most important aspect of knee protection is actually putting it on. I often leave them off when riding less aggressive/rocky trails but I know it's a mistake.
In Wisconsin the season is short so there is rarely an excuse not to ride. Although our local trails in Green Bay drain pretty well, I would rather have to repair the trail than miss out on a ride. We can all lend a hand to make better trails.