Durston ring mandrels, ranging in size from 3mm to 10mm, are made from hardened steel and hardened to 64 RC using an induction hardener.It is unmarked, ground and polished to ensure long lasting durability and smooth use in a professional workshop or factory. With a length of approximately 380 mm and a weight of approximately 0.1 kg, the mandrel accurately measures rings with diameters ranging from 3 mm to 10 mm, providing reliable performance for ring shaping and sizing tasks.