1,Excellent Cutting Ability: Made of heat treated and tempered high carbon steel with Ti coating, which bring excellent cutting ability 2,For Various Materials: Hole saw bit kit can be used for steel, aluminum and other metal, plastic or wood materials 3,For 15 Degree Chamfer: Drill bit hole saw support enlarged or countersunk hole, deburring edge, and 15 degree chamfer 4,16 18.5 20 25 30mm Opening Diameters: There are 5 opening diameters, which is 16 18.5 20 25 30mm, so that will meet your different using needs 5,With Hex Wrench And Spring: Equipped with hex wrench and spring, which is convenient for you to install, disassemble and use 5 x Metal Hole Saw Bit5 x Hex Wrench5 x Spring Item Type: Metal Hole Saw BitMaterial: High carbon steelSurface Treatment: Ti coatingHole Diameter: Approx. 16mm or 0.63in 18.5mm or 0.73in20mm or 0.79in25mm or 0.98in30mm or 1.18inShank Diameter: Approx. 8mm or 0.31inUses: Steel, aluminum and other metals, plastics or wood Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement.