amoolo cobalt drill bit set (1/16"-1/4",13 pcs), m35 hss metal drill bits for steel, stainless steel, hard metal, cast iron, plastic and wood amoolo amoolo m35 cobalt twist drill bit set 13 pcs 【specifications】 −material: high-speed steel m35 cobalt (5% cobalt) −split point: 135° −process: fully ground −flute type: spiral −shank type: straight round shank −applications: perfectly suitable for hard metals, such as stainless steel and cast iron 【what does the set include?】 13 most commonly-used sizes - 1/16” (1.59mm); 5/64” (1.98mm); 3/32” (2.38mm); 7/64” ( 2.78mm);1/8” (3.18mm); 9/64” (3.57mm); 5/32” (3.97mm); 11/64” (4.37mm);3/16” (4.76mm); 13/64” (5.16mm); 7/32” (5.56mm); 15/64” (5.95mm); 1/4” (6.35mm) 【what is m35 cobalt?】 ►the addition of 5% cobalt increases drill bit’s heat and wear resistance, which makes it perfectly suitable for stainless steel and cast iron. m35 cobalt steel drill bits can penetrate a 5mm-thick 304 stainless steel plate in 5 seconds. ►while the 5% cobalt makes the bits much more durable,it also makes them more brittle than ordinary hss bits under improper usage. 【how to use this drill bit? here are some warm tips】 ►keep the bit vertical and fixation while drilling. ►to avoid drill bit break, 1/16” or smaller bits are suggested used with pin vise. ►pay attention to the cooling of the bit, adding water or coolant when drilling can increase the life of the bit. 【warranty: 90 days】 no worries! your satisfaction is our ultimate goal. if you have any questions or concerns about our products, please do not hesitate to contact our customer service team support@amoolo.com, we will respond within 12 hours. 【why choose amoolo?】 amoolo - craft the future! amoolo is one stop shop for all tool accessories. we have years of oem experience for international well-known brands. we are committed to providing the best quality products at a affordable price. amoolo is always by your side to craft your desk, living room, home even the future!