Feature: 1. [Durable High Speed Steel] Made of high quality high speed steel material, sturdy and durable, long service life. 2. [Three Blades Design] Inner, middle and outer three blades design, higher efficiency, not easy to collapse. 3. [Inclination Angle Design] Inclination angle design reduces friction and reduces the temperature of the knife. 4. [Evacuate Chips Smoothly] Evacuate chips smoothly, greatly reducing jamming and tool breakage, and stable performance. 5. [Applicability] Suitable for metal openings such as cast iron, steel plate, thick stainless steel, thick non standard iron, etc. Specification: Item Type: Hole Saw Material: High Speed Steel Handle Diameter: Approx. 10mm / 0.4in Total Length: Approx. 90mm / 3.5in Working Depth: Approx. 25mm / 1.0in Uses: Metal Openings for Cast Iron, Steel Plate, Thick Stainless Steel, Thick Non Standard Iron, Etc.. Package List: 1 x Hole Saw1 x Hex Key1 x Storage Box Note: 1 Check the integrity of the hole drill before use;When the 2 hole drill is installed in the electric drill, the three faces of the corresponding shank should be clamped;Keep the verticality of the hole drill and the workpiece when drilling with a 3 hole drill4 Use a small feed force when starting drilling, and use a medium feed force after positioning;5 When drilling, the speed should not be too low to avoid jamming of the knife edge and causing tool collapse;6 When the center drill drills through the workpiece, the force should not be too large to avoid violent collision between the blade and the workpieceAfter the 7 hole drill drills through the workpiece, the workpiece should be withdrawn while the hole drill is rotating8 When drilling continuously, use cutting fluid to cool the cutting edge.9 Manual measurement, there is an error of ±3mm