By far, these are the most comfortable flip flops I've ever worn. The arch support feels very good and my heel doesn't roll or slide at all. The padding is not too squishy and not too hard. They also look relatively cool and casual, like the ones I'd buy at surf shops, though perhaps not quite that cool. They are stylish without being too formal or fancy.
My pair, size 12, seems about 1/2 a size smaller than that, but I anticipated this based on reviews elsewhere. I normally wear 11.5, and these 12s fit great. I'd gladly pay retail ($50) for these, but look for deals. I found them for $32 with shipping.
I've had plantar fasciitis for 7 years (a fallen arch and heel pain). As a result, I can't walk barefoot for more than 5 minutes without developing heel pain. When I am not at work, and sometimes when I am, I constantly wear running shoes with added arch support. These flips, with nothing added, feel just as good on my bad foot as a running shoe with added support. My toes can get sun again!
They claim, with reason, to be environmentally friendly. I don't know if average flip flops contribute to global warming, so I'll just take Chaco's word for it.
