Material: HSS, surface treatment: Titanium plaage Titanium coated to reduce friction and a high speed steel heat Set includes 1pc 15 step bit (4-32 mm), 1pc 9 step bit (4-20 mm), 1pc 13 step bit (4-12 mm) It is very convenient to use for drilling holes in a variety of materials such as steel, brass, wood, plastic etc. Package Included: 1 x Set of 3 conical Titanium Drill HSS Titanium 4-12/20/32 mm (included a nylon bag) Product description Warm Tips Pls cool down with water when working because of the high temperature,so that the validity period can last longer. The speed is advised to be 250-400 RPM/Min Cut through wood, sheet metal, steel and other surfaces thickness under 5mm. Length: 5 Step Bit: 4-12mm,Length: Approx. 6.7cm/ 2.64" 9 Step Bit: 4-20mm,Length: Approx. 7.4cm/ 2.91" 15 Step Bit: 4-32mm,Length: Approx. 10.2cm/ 4.02" The 3 Cutters Come in the Following Sizes: 5 Step Bit: 4-12mm (4mm, 6mm, 8mm, 10mm, 12mm); 9 Step Bit: 4-20mm (4mm, 6mm, 8mm, 10mm, 12mm, 14mm, 16mm, 18mm, 20mm); 15 Step Bit: 4-32mm (4mm, 6mm, 8mm, 10mm, 12mm, 14mm, 16mm, 18mm, 20mm, 22mm, 24mm, 26mm, 28mm, 30mm, 32mm). Package included: 1 x Set of 3 pcs Titanium Drill Titanium Hss conical 4-12/20/32 mm (included a nylon carrying bag)