I?m a 12 WW women?s and I got the 45. Instant hanging space for changing clothes or drying. There is no aux input, but Im more concerned with having a headset that will not fail on my when I start soloing. When it arrived, I took it out of the box, unplugged the ?nest? and attached long charger component to base unit. Even on the boat they stay dry and don?t hold water, yet they aren?t slippery either. I even tried using this in combination with the lotion but by the time I get home there is still a lingering smell. Bad customer service and a product that I?ve spent $30 on that doesn?t work! I thought I was done slipper searching, but I cant chance this happening again, so Ill be looking elsewhere for my next pair. They last, are easy to clean and are well worth the money! They also have a hard plastic sole that has no traction, the opening around your foot has a edge that cuts into the top of your foot.