COBALT JOBBER DRILL BITS:115 pcs high speed steel with 5% cobalt drill bit set can resist high heat abrasion while drilling. M35 cobalt HSS twist drill bits is more suitable for hardened working material. Particularly adapt to drilling stainless steel, cast iron, high temperature alloy, titanium alloy and even hard plastics, and woods. Can also be used for soft materials. TWIST DRILL BITS: Premium HSS with 5% Cobalt and 135° split point drill tip design guarantee 115 pcs drill bit keeping sharpness while drilling hard materials and prevent tips walking on the working surface. Proper twist and flute design clears chips and particles fast. WIDE APPLICATION: HIGHFIRE115 pcs set with sharp and hard cutting edge is ideal for versatile application especially for projects made from hard material, such as kitchen utensils, machine parts, medical equipment, DIY projects and so on. ORGANIZED HOLDER: The whole drill bit set is kept in one iron case with size index holder for easy storage and organizing. DRILL BITS SIZE: 115 pcs set includes 29 pcs fractional sizes from 1/16″ to 1/2″ by 64ths increments; 26 pcs letter sizes from A To Z; 60 pcs wire sizes from #1 to #60. Almost cover all sizes you would use.