Great for repairing damaged bolts and fasteners Hard steel could use lubricating oil to improve tool performance. This external deburring chamfer works by a way of shearing metal layer by layer. Using the lowest speed on the drill bit, and then slightly applying pressure to remove the burr. Safety conscientious design means no cut hands, no , and no . Applicable to hardened steel, mild steel, copper, aluminum rod, wood rod and hard plastic rod. Colour:Black Material:Tungsten steel Package Contents: 2 * Deburring External Chamfer Tool Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.