5 and I decided to buy size 10, but it was tight. There isnt a way to lock the phone on mute. After reading reviews, I was a bit skeptical but decided to get 5. It arrived quickly, it was very well packaged and presented. The sound quality is better than I expected from small, modestly priced headset. After balancing the tone arm, adjusting the counter weight and anti-skating, I proceeded to adjust the cartridge using a turntable protractor. She wears a size 8 so I got the 9/10. UPDATE 8/5: One month of use and the left earbud no longer charges. Scent did not last long. I went on a moderately difficult trail, and these shoes did very well.