YanSheng 6542 High-speed Steel 3-Blade Rose Reamer / Stepped Drill - Silver (20.5 x 90)
High-speed steel 4241 suitable for the workpiece with the hardness below 25 degree such as carbon steel sheet iron plate insulation board PVC board plank; High-speed steel 6542 suitable for the workpiece with the hardness below 28 degree such as Aluminum stainless steel; Surface treatment: Super Carbon WRB