For openable size bangles only one size is 6cm , openable size measure way is that find one soft ruler to around you wrist , if your wrist lenth is 15-18cm , the size 6cm bangles is proper for you . For fixed size have 3 sizes(S 6.4cm/M 6.8cm / L7cm) , the bangles cannot open, you can get the size from the product discription .

b210 is big size for big hand , the inner diameter is 7cm/2.76inch

Hi, No they have not turned so far and I wear them nearly everyday. I’ve bought jewelry from other vendors after purchasing these and they did turn. Overall, I would recommend this set over any. It’s beautiful and i always get compliments when I wear them. I hope this helps. Thanks