Solid aluminum mandrels are perfect for measuring the size of rings. The mandrel with a groove is useful with rings that have stones set low in the ring with the culet exposed underneath. This aluminum mandrels is not strong enough to withstand blows from a hammer, so it is not to be used for reshaping or working on rings.
This American made mandrel is marked with sizes 1 to 13 in 1/4 size increments.
The mandrel is approximately 13" long.