Main material: aluminum alloy Drill bit: 9.5mm (3/8inch) Features: Convenient and flexible to use: The punching position can be adjusted up and down, with built-in clamping function, making it efficient and fast to use! Double scale: Metric and English double scale markings, designed for more user-friendly! Left and right positioning: With adjustable side positioning function, the wooden board calibration is more accurate and efficient!