This PCB Drill Bit Set contains 10 different size drill bits diameter: 0.3mm, 0.4mm, 0.5mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.1mm, 1.2mm. And each size have 5 pcs. Varies sizes to meet different needs.1.This micro drill bits are designed to drill and engrave on print circuit board and other precise work. The PCB Drill Bits are made of high quality tungsten steel, highly wear resistance, high hardness, bending strength, anti-impairment, highly working efficiency. Seismic design on the blade edge enables it to stay stable during engraving. 2.PCB Drill Bits Set are great for punching at printed circuit boards, 3D Printer Nozzle Cleaning, CNC engraving plexiglass, Amber beeswax, bakelite, jewelery, metal plastic and other precision drilling; cutting and engraving and worked on Acrylic, PVC, Nylon, Resin, Fiberglass,etc. 3.PCB Drill Bit With sharp cutting edge, milling groove and clean surface, these sets of tool work quickly and cleanly, no glitches or scrap left. Package with high quality plastic box, easy carry and better protection keeps the blade tip goods in the delivery from being damaged.1. High quality material The PCB Drill Bits are made of high quality tungsten steel, highly wear resistance, high hardness, bending strength, anti-impairment, highly working efficiency.  2.High Precision With sharp cutting edge, milling groove and clean surface, these sets of tool work quickly and cleanly, no glitches or scrap left.  3.Portable & easy to store The hand drills set is small in size, so you can store them in your toolbox easily and use them anywhere. Clean surface, not easy to crack.1) PCB drill bits which below 0.5mm are easy to break because they are small and thin. It is recommended to be careful when using them. 2) Don't use on too hard material,like high hardness iron. 3) You must apply force evenly and vertically while using. Do not touch the blade with your hands or external force to avoid damage.