TevaWomen's Original Universal Sports and Outdoor Sandals

What is the width at the widest point for sizes 6-8 please? I have 25.5cm length feet but 10.5cm wide and would like to know if these would fit.

Should I buy one size up? Also, are these ones plain black or shimmery, both are pictured?

How do these fit for size? I'm normally a 4 and a half and don't know whether I should size up or down - any advice?

Is the sole flexible or firm? Is the traction good? Thanks