The set comprises a selection of 19 excellent quality metric drill bits made from quality Swedish M2 grade steel and housed in a robust plastic case. They have been heavily tested by our manufacturing department and are suitable for many materials up to and including hardened steels to HRC-30. We have found them to be so impressive that they are now being used in our manufacturing process and on our engineering courses. These bits are ground from solid high speed steel bar and offer excellent chip clearance, rigidity and quality of cut. Perfect for general workshop and production use, they are also available in a large **** of metric and imperial sizes. Remember to use coolant when appropriate. Outside diameter tolerance of H8 within ISO 286. This gives a close running fit. Sizes **** from 1-10mm in 0.5mm increments.