Tall, sterling silver 'concave' ring. This ring narrows towards the back, and is flattened on the sides to ensure it fits comfortably between your fingers.
It measures 13mm tall at the front.
This ring can be supplied 'open' to fit most fingers (by either squeezing it together, or stretching it out a little), or it can be made at a particular UK ring size. The picture shows an 'open' version.