HIGH MATERIAL The hole saw arbor is made of high quality M42 HSS High cobalt ductile high speed steel and Bi-metal steel with sharp edges and high hardness.Strong and sturdy.Durability and good stability. SPECIAL DESIGNHole saws High-speed steel cutting edge provides shock resistant teeth and resists tooth strippage. Soft, spring steel creates a flexible backing material that allows the hole saw to absorb impacts of the job of drilling holes in difficult-to-cut materials. WIDE APPLICATIONThe hole cutting set suitable for cut Wood Mild Steel, Stainless Steel, Cast Iron, Brass, Aluminium,etc. Large chip holeThe holesaw has removal groove,hole saw sets can discharge the chip rapidly,improved the speed of removing the cylindrical iron filings in the hole and will not cause the crack and stuck piece phenomenon. NOTE The maximum working depth of the product can reach 34mm, which is suitable for drilling holes on bench drills, drill presses, and electric drills. Please remove the spring when processing thickness of more than 10MM.