[Made of High Speed Steel]: Premium material and surface treatment ensures the durability and sharpness. This unibit can drill holes on Iron, Aluminum, Copper, Plastic, Wood, or anything that has similar or lower hardness as these materials. [No Pilot Hole Required] Self-starting & non-walking spilt point tip design helps you start drilling quickly. [Non-stop]: Our Polished Steps and Size Highlights let you able to see target hole size during drilling. No need to stop in the middle of the drilling and check. Save you time and hassle. [Non-stop]: Our Polished Steps and Size Highlights let you able to see target hole size during drilling. No need to stop in the middle of the drilling and check. Save you time and hassle. [Multi Hole Sizes]: This step bit comes with 12 marked sizes so you can drill 12 different hole sizes, saving you time and effort to change bits. Marked sizes including: 3/16", 1/4",5/16",3/8", 7/16",1/2",9/16",5/8",11/16",3/4",13/16",7/8" [Know More About Us]Jearx tools is a professional step bits manufacturer and all our step drill bits are all made of HSS. We also provide the high grade & top grade step bits for stainless steel & other thick material. Visit our store to know more tools! HSS 1/4 - 7/8 Inch High Speed Steel Step Drill bits, Doubles Flutes Unibit for Hole Drilling in Iron, Copper, Aluminum, Wood, Plastic