5, so I got a 7-8, and they do move around a little as I walk fast . I?ll be doing that for another bike. It drives me mad when the little plastic nozzles fall off my $200 earphones, never to be found again, rendering the earphones almost useless. When I turned the Noise Cancellation ON, the sound came to life: the bass was tighter, the midrange was clearer and the treble was sweeter. I returned mine with no problems. This is partially due to the lightweight construction. I get a ton of compliments on them (I think the double strap and color combo is particularly cute), and I can do any activity in them for hours ? standing, walking, hiking, shopping, biking. I have tried sanding them down with a nail file. ??????????? Pretty basic.