These are the first knee guards I've worn that actually don't get in the way while riding. I used to have a pair of older Thor Force guards that were hinged, but didn't offer nearly as much coverage, and the hinge was clunky...they made you walk like a robot and they rubbed on your shin constantly, to the point of being downright painful to wear. As such, I never wore them, and several times I wished I had.
However these Fox guards are super comfortable and I forget I'm even wearing them after a few minutes. Can easily wear them all day with no discomfort. The hinged knee works well, it allows you to fully bend and straighten your knee without binding. The guard also stays in place very well, others I've used tended to slip down constantly, a big annoyance. They're very lightweight and are extremely well vented so they don't get hot either. Coverage is great and the shin guard fits perfectly with a 50/50 or "shorty" boot. Rocks and roost bounce right off and you never even feel it.
The only complaint is that since the actual knee coverage is "floating"(the shell doesn't contact your knee), kneeling down and putting weight on the knee shell feels like it might break the rivets that hold it on.
At $65 they're definitely premium priced(though cheap compared to the Thor Force guards at $85-$100), and MSRP seems to be the rule....no bargains to be found anywhere. Still, for a knee guard that is actually comfortable to wear and isn't more of an annoyance than it's worth, it's really not bad.
These work ok, but could be better. After a few hard hits, the rivets will break. The inside padding will pull away. The straps are not in the best location for MY legs, and they tend to want to fall down a bit too low. Figure these last 1 full season and time to replace.