HavaianasLuna, Comfortable, Stylish, and Functional Sandals, Secure Ankle Fit, Braided Straps, and Non-Slip Sole, Women

Why are these so cheap

Hi what size to get if I'm 5.5-6

I'm a uk6 - so should i go for 6/7uk according to size chart here?

Sorry if a silly question, but does the back strap stretch, concerned they may become too loose. also size 7, foot is 25cm - what size is best