With Cordura outer fabric and internal hardcap protection the 661 Comp AM Knee Guard offers great protection for aggressive trail or all mountain riding.
I always wear 661 knee and shin guards. They've saved my butt several times. I always wear L, and they always fit great. However, they must have changed their sizing as L was way too small. I noticed that there is now an XL option, this is new. I suspect they've made L a little smaller, maybe XL is a little bigger. Otherwise pad is nice, very smooth surface with nothing to catch on anything. No side pads (like the Kyle Straights they replace) but otherwise a nice, comfy guard.
Ended up going OTB wearing these and they protected my knee from the initial impact, but slid downwards as I ended up with my head pointing down hill and rolling. I've got rock road rash all over my knee cap. These seem to be sufficient for XC/maybe mild dirt jump, but rocky tekno / REAL all mountain riding is a no go. Ill stick to my 661 comp full knee/shin hard plastic armor. Maybe EVO's are next.
I love these pads. I only have one 2hr+ ride in them, but I'm amazed at how comfortable these are. I forget they are even on during long uphills, and push it a little harder in the downs knowing I have knee protection. Exactly what I was looking for as an everyday aggressive free-ride pad. No idea how they hold up in an actual crash just yet. Being that its currently winter, I have no heat complaints. Ventilation seemed fine but wont really know till summer.