416 stainless steel hexagon bar is a type of stainless steel bar that has six sides and a hexagonal cross-section. It is made from the 416 stainless steel alloy, which is a martensitic, free-machining stainless steel alloy that contains sulfur. The addition of sulfur enhances the machinability of this alloy, making it easier to machine and cut. Diameter is measured across flats.