Hexagon bar is a hexagonal (six-sided) cross section, size (Diameter) is specified by the distance across the flats.
416 stainless steel alloy 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.

Material: Stainless Steel
Shape: Hexagon Bar
Alloy: 416
Temper: Annealed
Diameter: 0.437 (7/16 inch)
Finish: Cold Finished
Specifications: AMS 5610, ASTM A582
Tolerances: Diameter: (+0/-0.003) | Length: -0/+0.999)