Product Description AUTO-DELLO drills are made from alloyed cobalt tool steel R6M5K5 Cobalt 5%. The cobalt in the steel composition allows it to maintain hardness at high temperatures, which is especially important when drilling difficult-to-machine stainless steels. - Have high wear resistance. - The tips of the drills are cross-shaped ground at an angle of 135°, allowing for drilling of high hardness metals. - Hardness 64-67 HRC. - Packed in an envelope with a hole for convenient storage. Using drills with increased wear resistance and hardness allows for significant time savings in drilling and greatly simplifies the work of the car mechanic.