CONSTRUCTION GRADE: The hole saw is made of M3 high speed steel and Bi-metal, With higher hardnesshigher toughness and stronger resistance. The 6 inch hole saw comes with a heavy duty 7/16' hex shank mandrel, fits 1/2' drills SPECIAL STRUCTURE: The hole saw blade is designed of the non - binding clean edge, so you could make a clean holes smoothly. Duplex smooth of Positive rake with variable pitch guarantees a fast and clean cut through all thickness. HIGH PRECISION - Upgraded design with ultra sharp serrations for faster and cleaner cutting, which is ideal for soft wood, plastic plate, plater board and thin PVC board HIGH QUALITY MATERIAL: Carbon steel , Heat treated. High strength and hardness, design for increased durability and outstanding cutting performance. Our hole saw features a reinforced shoulder for added strength and long life PORTABLE STORAGE CASE: Hole saw kit with a tough box for easy and organized storage. Easy and convenient to carry. Improve work efficiently.