I purchased the X4 Knee Guards because the Pro-X3's were not available in my size (rarely is there much of a stock of the Pro X3's). All went well on my first 4 or so rides except for a little irritation on one knee, but this last time my knee was rubbed raw. I thought adjusting it would help, but it then started to rub raw another section. I had to turn around and end the ride after only going out for 3 miles. I am hoping that at the end of this review there is a place for me to submit a picture of my knee. Three days later and it still hurts. I'll stick with the Pro-X3's if they ever have my size in stock. In the meantime, I'll ride with a worn out pair.

They do the job and are comfortable, however they tend to pinch the skin under the knee.

Not the greatest in terms of durability. Had a pair about a month and the second a couple of pins from a pedal snag the mesh on the back, it's game over. At least with the Pro Rugged you can sew them. They also rub quite a bit just below the front of the knee. Pretty disappointing.

I have used G-Form's MTB knee guards for many years. I have gone through many iterations of them with the last being the X3. I like how they are soft and can be worn for all day ride without any chaffing or discomfort. The only negative of the old ones is that the seem between the rubber and the lycra mesh would eventually tear. I was about to purchase another set of X3 when I saw that the X4 version was available. They arrived and low and behold they are completely redesigned and are nothing like the old ones. The rubber is now encased in the lycra, which will likely last longer. HOWEVER the rubber is way harder than the old material and is setup so it is in front of your knee with an air gap rather than comfortably wrapping your knee. This combined with the fact that it is way harder and internally covered with bumps or ridges means that it rubs very uncomfortably on your knees now and then while you pedal. If you like the old ones, these are Not the same. If you like other brands, these may be similar...

Fit perfectly, and provide better confidence.