Superior Quality: Made of high quality cemented carbide, which ensures high hardness, anti-rust, sturdiness and durability. High Precision Drill Bits: Highly shock and wear resistant and ensure a smooth cut. Sharp and cut resistant teeth with low consumption for a long lasting product. Intelligent Design: Adopts the central spring design. It can control the feed amount and helps to remove chips, preventing damage to drill bits. The drilling efficiency is higher with the hexagonal handle and can be locked firmly. Multi-purpose tools: This hole saw set is suitable for bench drill, magnetic drill, pistol drill, impact drill, etc. Perfect for stainless steel plate, square tube, iron, cast iron, wood, GRP and other general sheet metal. Dimensions: 16mm, 22mm, 30mm, 40mm, 50mm, 60mm to meet your different needs.