【 Comprehensive Size Requirements Combination Set 】 Contains 5 sizes: 1/4 "(6mm), 3/8" (10mm), 1/2 "(13mm), 5/8" (16mm), 3/4 "(19mm), all bit designed with 1/4" hex shank Very suitable for drilling variable sizes hole of metal 【M35 HSS Metric Drill Bit Set】each metal countersunk drill bit is made from high quality M35 HSS material,countersink drill bit set is excellent in heat,providing excellent cutting ability. 【Unique Five Blade Design】Countersink drill bit set all adopt a unique 82 degree five blade design, which can better reduce vibration and burrs, and smoothly discharge debris, suitable for all types of drill bits and mold grinders. The variable speed drilling rig is easy to control, allowing you to work smoothly with the drill bit without obstruction 【Can penetrate multiple materials 】Our drill bits for metal can be used for drilling medium hardness stainless steel, copper, aluminum, plywood, cork, hardwood, and fiberglass. These countersink drill bits work hard on the foundation processing, achieving actual countersink holes and allowing the screw heads to be flush and even with the surface of the material being utilized Can Penerate Multiple Materials.