Features: 5 SIZES: 16mm / 0.62 inches, 18.5mm / 0.72 inches, 20mm / 0.78 inches, 25mm / 0.98 inches, 30mm / 1.18 inches. Chunk Size: 2/5-inch(10mm) HIGH QUALITY MATERIAL: Made tungsten carbide bits, Using hard alloy (tungsten steel) material, with high hardness, high wear resistance, high strength, smooth cutting edge, bending resistance, resistance to damage and other characteristics, especially impact resistance, Openings for stainless steel, iron, aluminum and various types of pipes. INTELLIGENT DESIGN: Hole cutters use spring design, which is convenient for removing chips, superior drilling efficiency; with hexagonal handle. With a spring, the drill will not get stuck during use. FUNCTION: High Speed Steel hole saw set is specially designed for thinner steel bits, ideal for installing locks, knobs in doors and cabinets or drilling larger diameter holes, Hole Saw Set for Suitable for installation on handheld drill bits, bench drill bits and so on . For stainless steel plate, square tube, iron, cast iron, wood, F.R.P and other general sheet metal.It widely used in wood, PVC pipe, plastic, plaster, like home bedroom, wall surface, glass wall edge, kitchen, kitchenware, sink edge, acrylic words on the facade outdoor , etc. NOTE: Using lubrication or water to aid cooling can extend the service life of the hole saw