This arm band is pretty good. As long as your using it for just running or any other activity where you're not using your arms that much, it is great. I wear it to the gym for when I'm on the treadmill. However, when I get off the treadmill to use the lifting machines the arm band isn't that great. It tends to slip off my arm when doing various arm machines. I think there could be more velcro on the arm band. There is a very thin strip around the middle of the strap that has velcro on it. I may go purchase some cheap velcro to glue on so the arm band will stay on. The fit of my 4th generation nano isn't perfect, but it fits in the holder and I am still able to use the wheel through the open circle.