I have had 2 surgeries on my right knee and if I hike or bike for long distances without a brace it swells badly. This thing works great for me, it keeps my knee in place and prevents it from swelling. I carry an extra one in my backpack just in case.
The only bad thing is your knee sweats badly from the neoprene and doesn't smell the best after a few outings. You can rinse this in soap and water to clean it.