Durable & Sturdy ----- Solid M2 high speed construction for extra durability, close to impossible to snap compared conventional drill bits, the unique 3-sided shank prevents slip in drill chuck and reduces shocks; oiling the bits recommended before every use to maximize the service life. | Jam-Free Performance ----- Dual-flute design and three-sided shank design is optimized for cordless drills in high speed provides greater speed and control while minimizing steel scurf flying around, to lengthen service life, please do not set drilling speed at its maximum to avoid damage to the cutting edge. | One Bit for All ----- The bit comes with 19 sizes so you can drill up to 19 holes with different diameters from 3/16 to 1-3/8 inch(3/16", 9/32", 3/8", 7/16", 17/32", 5/8", 11/16", 25/32", 7/8", 29/32". 31/32", 1", 1-1/16", 1-1/8", 1-5/32", 1-7/32", 1-9/32", 1-5/16", 1-3/8"), saving you time and efforts to change bits, quadrupling your drilling efficiency compared to competition. | Laser-Engraved Marks ----- All the laser-engraved reference marks make it easy to stop on any hole size for your convenience. | Universal Compatibility ----- Designed for drilling on steel sheets up to 0.2 in., acrylic, PVC and wooden boards up to 0.2 in.