Hex bolts have a chamfered point to aid insertion into a tapped hole or nut. Length is measured from under the head.
Stainless steels are used for their corrosion resistance, high-temperature strength, scaling resistance, and low-temperature toughness. These properties account for their extremely wide use in practically every industry. Austenitic Stainless Steels are alloys of iron and carbon that contain between 16% and 30% Chromium, a maximum of 0.15% carbon, along with Nickel (or Manganese), and other alloying elements. The chromium, which helps develop a passive surface oxide film, provides corrosion resistance in stainless steels. Austenitic Stainless Steels are designated by a 3 digit SAE Stainless Steel Grade beginning with the number 3 (e.g. 304, 316). Another common naming convention for Austenitic Stainless Steels are 18/8, 18/10, 18/0, etc. where the 18 refers to the % of Chromium and 8 to the % of Nickel contained in the material.
Hex head fasteners can be driven with simple wrenches, and require minimal clearance above the fastener because they can be driven or loosened from the side.
A threaded fastener's size name includes information about the major external diameter, followed by the threads per inch, which indicates if it is coarse or fine.