I wear a size 6 in Vionic shoes, and I have several pairs. They run really small. As transparent a set of headphones as Ive ever heard. If you really want to use the carabiner, Id also use a thick black rubber band to ensure the case stays closed. It remains at 100% the entire time. Had to get a replacement for my headset I asked my son to tell me his "review" on these as I purchased them for him. If I ordered another pair, I would order a 9. They also work well on phone calls. Sadly I had to return it.