Ring Mandrel this mandrel is for square ring shanks. It is graduated from 12mm to 24mm. Can be used for holding, shaping and straightening rings. This mandrel is also finger shaped, meaning corners offer a more natural and comfortable fit. A plain hardened steel mandrel that can be used for shaping straightening and enlarging rings. Also for gauging and holding rings while stone setting. This mandrel is extra hard for superior performance for forming.