My heels have been killing me for a couple of months.  I've been going back and forth between Chacos, Birkenststocks, and Vionics which is better than nothing but I tried to go for a walk yesterday and had to come back home, my heel felt like a bruise that was on fire and I could barely stand it.  My husband had a pair of these flip flops and I put them on and it felt good enough that I ordered my own pair.  They came today and just in time.  I've been wearing them all afternoon and I can walk without wanting to scream so it's a big improvement.  The bottoms of his are slightly different and I guess mine are in women's sizes and his are men or unisex.  I got an 8 in the women's, which is what I normally wear.  I believe if I got the unisex ones I'd be a 7.  Not sure about that but you can call Telic if you need an answer.  I called them because mine felt much stiffer than my husbands but the rep told me that within a couple of weeks mine will feel that soft too.  She said the material is heat activated and they'll soften up and shape to my feet.  Anyway, I'm happy to have them.  Just hate for summer to end because then I don't know what I'll do.  Maybe these will help my feet heal by then.