The ring is a 3d mobius strip of an endless loop, representing an infinte cycle, like our life and love. The direction-shifting surface gives the ring more changes and dynamic. It happens on ring crown and turns to flat on ring circle to offer the wearing comfort. The ring is Size 12.5(Inside diameter is 21.8mm). Please don't hesitate to contact me if you want other size. For the ring size, please refer to the chart below: http://www.ringsizes.co/.