These are by far the best boots that I've ever owned.  All of the other side-zip models fail on me due to my orthopedic condition on one of my ankles that requires my wearing an internal brace.  This puts a tremdous amount of stress on the zipper.  BUT these boots are amazing.  I've worn them every day without any problems with the zipper, which is proof that these boots are bulletproof.  The heals and soles are extremely grippy, and give you a very secure feeling.  I'm a cameraman, and have to carry lights, cameras, tripods, etc., etc., across fields with rocks, dirt, mud, grass, etc., as well as up and down hills and extensive stairs.  I've been on my feet all day today, wearing these boots, and I'm feeling just great.  In short, there is no more extreme case than mine.  And if these boots work for me, they will work for anyone.  I can't say enough, so I'll just give another five stars:  *****