The bi-metal hole saw produces smooth cuts in various materials. The tooth geometry (Vario tooth design) is ideally suited to glide through the material and create smooth cuts. This hole saw is made from bi-metal HSS (high-speed steel) with an 8% cobalt alloy, resulting in a lower risk of tooth breakage and higher heat resistance for long-lasting cutting performance. This hole saw is suitable for cutting wood, metal, and plastic. The bi-metal hole saw fits all standard adapters on the market. Diameter mm: 79, Diameter inches: 3 1/8, Working length mm: 44.