✅【Five-blade design】Each countersunk drill adopts five-blade blade design, which can reduce vibration and prolong life, achieve smoother drilling, with 1/4" metal hex. ✅【Compact Grinding】Precision grinding 82° tip for drilling holes on most medium hardness stainless steel, copper, aluminum, wood, plastic. ✅【M2 HSS Cobalt Layered Drill Bits】M2 Cobalt Coated, each metal countersunk drill bit is made of high quality M2 HSS material, this countersunk drill bit set is excellent in heat, corrosion and rust resistance to reduce friction and run cooler. ✅【Universal Compatibility】Surface black oxide treatment increases corrosion resistance, and the five-blade design helps create a strong connection between the screw and the material. ✅【Clear Sizes】Meticulously crafted drills with very high visibility numbers available in very common 1/4", 3/8", 1/2", 5/8" and 3/4" drill sizes. ✅【100 extra-long warranty period】：if you have any questions about the product, please contact us and we will answer you within 12 hours. If the hexagonal handle breaks, refund or replace for 100% . ✅【M35 Cobalt Superhard High Speed Steel】: ISI M35/1.3243/SKH55/M35 steel is a kind of high speed steel containing cobalt, which has the characteristics of high wear resistance, high pressure resistance and sintering resistance. ✅【100 extra-long warranty period】：if you have any questions about the product, please contact us and we will answer you within 12 hours. If the hexagonal handle breaks, refund or replace for 100% . ✅【M35 step drill compatibility 】： step drills can quickly and smoothly drill holes of different diameters, such as stainless steel, aluminum, wood, plastic board (the board must be thinner than the height of the step drill) ✅【M35 four spiral groove】: step drill four cutting blade design. Faster, smoother cutting and easier separation of sawdust.