I had a severe grade 2 sprain of my MCL about 5 months ago after looping-out upon landing a double. No surgery, but lots of physical therapy. I have been wearing the POD K300 for about a month. I have about 8 hours of trail riding on it. I also wear the brace at the gym while doing cardio and plyometric workouts (running, jumping, kicking, etc…). I wear it at work, too. Here are my thoughts: POD says that proper fit is very important and they are not kidding! If the brace doesn’t fit you right out of the box, there isn’t much you can do. There are some small pads you can play with, but basically if the shape of your knee isn’t compatible with the POD, you are dead in the water. All brands of rigid knee braces seem to be like that. I suggest you try on several different brands before buying. If you buy off the internet, be prepared to return the first one or two. Just like helmets, they don’t all fit the same. Having said that, the K300 fits me just fine (the Ultra Cell didn’t). The K300 is like all the other MX gear we wear; you notice it a little when you are standing still, but once you get moving, it becomes "almost" invisible. I notice the brace when I am squeezing the tank with my knees, but I've gotten used to it. Actually, it gives me confidence to squeeze the tank. The same goes for putting my foot out in a turn. I wear the brace at work, under cargo pants. With the patella cup removed, it fits... no problem. The velcro straps keep the brace in place very well. I was worried that it would slide down while riding or working out, but I can ride for over an hour before I notice any movement. And, if I have to fiddle with it, I just reach down and pull it up… no need to drop my pants…it doesn't move that much. It does not interfere with (or touch) the top of my boot. I can do a 45 minute plyo workout without having to mess with it at all. The straps do their job; however, if you have hairy legs, buy a knee sock otherwise the straps will pull on the hairs around your calf and thigh. The design of the patella cup is my only complaint (thus 4 stars). It is made of plastic and is designed to "snap" into place over the knee. That is good and bad. It is easy to remove it when going to the gym. But, when in place, the cup seems flimsy. Also, when the knee is at 90 degrees, the patella isn’t completely covered. If your main concern is patella protection, take a look at it before buying the K300. Maybe the engineers know something that I don't know, but the cup seems flimsy. The appearance of the K300 is top notch…very impressive. They spared no expense on appearance. All the parts are tight and it is very light weight. The color scheme, stickers and logos all look great. The pin-stripes look like they were hand-painted (by a pro…not a hack). You won't be disappointed by the appearance of the brace. Does it work? I hope I don’t have to test it on another hard crash. However, I can definitely feel the difference after a ride or workout. Prior to owning the K300, my knee would be really sore the day after a ride or hard workout. Now, with the brace, my knee is MUCH LESS sore. I have started saving money on ibuprophen. I like the brace, am glad I bought it and I would buy it again.