I heard great things about this shoes from youtube, but it did not work out for me.
On the back of the shoe, where you see that little loop, the fabric just under there is sharp and it rubbed against my ankle causing irritation leading to callus. This is a design flaw on NB's part.  Because I live in TX, shippping the shoe back to the seller in the UK would leave me a $10 refund.  I've decided to cut out the back with a scissor.