50 Sizes in 5 - The set includes five standard step drill bits that can replace 50 individual drill bits, you can process 50 different types of diameter holes with the five pieces.The set includes a sturdy aluminum case for secure storage and easy carrying. HSS and Titanium Coating - High speed steel makes it more durable than others, titanium coating makes it easy to cut steel plate, aluminum sheet, copper, plastic , wood and many other types of sheet metal with ease. Good Design: Triangular shank fits into power tool chuck securely and eliminates slippage. Two flute design removes splinters faster and allows particles to escape easily. A necessity for the family, DIYer or professionals - Perfect for home repairs and light jobs such as drilling holes in plastic, aluminium, copper and many other types of sheet metal. 4" 1/8-1/2" 3/16-1/2" High Speed Steel 4241 Multifunction HSS Titanium Triangular ShankHigh Quality Material: The step drill bit is made of high speed steel with high hardness and good resistance to corrosion. wear. Made of high speed steel with titanium coating to reduce friction and heat, more powerful and durable. money and more convenient.Wide Application: The triangular shank step drill bit is perfect for cutting holes in a variety of materials including brass, wood, plastic and more in 25 degree hardness and 5mm d 'thickness. Titanium twist drill bits are mainly used in wood, plastic and aluminum and M35 twist drill bits are especially suitable for high hardness steel such as stainless steel.Specifications:Material: 4241 high speed steel. 5 step drill bits:1/4-1-3/8" 3/16-7/8" 1/4-3/4" 1/8-1/2" 3/16-1/2".Quantity: 5 pieces.Contents:5 step drill bits. Note: The data are all manual measurement, please allow 1-3cm error, due to the light and display difference, there are will have some color difference, depending on the physical item received.