【Durable Material】Premium TCT carbide tipped hole saws, high-grade TiAlN coated M35 cobalt drill bit, ensure its high hardness, sturdy and durable. 【Unique Three Blade Design Hole Saw】MAKE EVERY HOLE SMOOTH. Hole saw tips with outer, middle, and inner blades, avoid blade breakage, make chip removal smoother, ensure sharper and more durable. 【High Quality Stepped Pilot Drill Bit】M35 cobalt material ensure hardness, strength and toughness. Titanium Aluminum Nitride‌ coating provide wear resistance and long life. 【Wide Application and Easy Operation】Compatible with various machines like bench drill, magnetic drill, and electric drill. Perfect for hard metal, stainless steel plate, square tube, iron, cast iron, wood, F.R.P and other general sheet metal；Caution: Cannot be used for concrete, tiles and stone.