The hole saw for woodworking is made of high-quality high-speed carbon steel; the material of the bi-metal hole saw is a heat-treated M42 bi-metal saw blade.The concentric circular arc design, high precision, and uniform tooth edge can extend the hole's lifespan. A special surface treatment involving heating and blackening prevents the hole saw from rusting.Features and applications of hole saws: Specially designed metal hole saws are durable, with sharp teeth and smooth chip removal.They are suitable for steel, castings, aluminum alloys and other metal pipe fittings, as well as for plastic sheets, galvanized pipes, fire extinguisher hoses, all types of wood, plasterboard, etc.Suitable for: bench drills, pillar drills, pistol drills, all kinds of hand drills, etc. CUTTING DESIGN High-speed steel drill bits and saws feature impact-resistant teeth that prevent tooth loss.The hole cutter set has a clean, unrestricted cutting edge that makes cutting easier. After drilling, the drill's spring automatically pushes the disc out of the saw, resulting in a cleaner cut. 40mm Drill Bit: The high-quality 40mm hole saw can be used for PVC plastic pipes, cork tables, plasterboard, furniture and cabinets, as well as for installing door handles and locks.The maximum cutting depth/thickness is 25 mm. Note: If you intend to use the hole saw for an extended period, check the speed accordingly. The speed is 1000 RPM, making the hole saw easy to operate at high speeds.The product surface is coated with a thin layer of protective oil (to prevent oxidation and rust). Take care not to get dirty and check the condition of the hole opener.The package includes] 1 metal hole opener (other products are not included).WarningAs the dimensions are measured manually, there may be a measurement error of 1 to 3 cm.Due to the wide variety of screens, the actual product may differ from the photo.