Evan F.wrote a review of Troy Lee Designs Catalyst X Knee Braces on June 10, 2014
Familiarity: I've put it through the wringer
I have been using a pair of these for dirt biking (moto) for the last 18 months or so. They have proven durable and comfortable. Many, many crashes have demonstrated their protection.
No brace will protect against an ACL tear (they attach to your skin, after all) because the amount of twist necessary to do that is really small. (DAMHIK) They are, however, excellent for LCL, MCL, and hyperextension injuries. I also find them to be very comfortable, especially for gripping the tank and in slow-speed falls where the bike is on top of me.
The velcro on these is especially high-quality--I've seen no decrease in its hold. They do develop a nasty stink, however.
The adjustable stops for extension and flexion are a nice touch.