General description Automatic Center Drill Bit with Hex Wrench Set includes 8 pieces designed for precise hole alignment in various woodworking projects. This versatile tool is ideal for creating clean and accurate pilot holes, making it suitable for use with quick disconnect adapters in applications such as wood window and door tapping. Technical specifications Material: Steel Color: Silver Sizes: 5/64 inch, 7/64 inch, 9/64 inch, 11/64 inch, 5mm, 13/64 inch, 1/4 inch Usage For optimal performance, it is recommended to use a low speed when drilling, ideally between 2000 RPM and 3000 RPM. Using a higher speed may cause the self-centering drill bit to fail and break. Other information Measurement allowed error: +/- 1-3 cm