Each bit has multiple diameters stepped on one bit, letting you drill holes from small to large without changing tools.
Practical up to a point — they excel at thin materials (sheet metal, plastic), but struggle on thick hardwood or heavy steel because the steps don’t clear chips as well as dedicated bits.
High-Speed Steel (HSS) Build
Most 6pc step bits are HSS or HSS-coated, meaning they resist wear and heat better than cheap carbon steel.