According to information listed under the product Overview and Specs tabs, we recommend half sizes order up
I am an 8.5 and have narrow feet with high arches. I typically order a size down--so 8 for me--for most of the shoe companies that don't do half sizes. I have a pair of sandals similar to the ZX-2 without the heel strap and I love mine. I wear them every day in the summer. I usually have to "break" them in again after the winter and that sometimes means blisters from the straps rubbing. But totally worth it to me. It's hard to find good quality shoes, especially sandals/flip flops.