- 18-8 , which can be 302, 303 or 304 stainless, refers to 18% chromium and 8% nickel content.
- 316 is more corrosion resistant than 18-8 because it contains molybdenum, but in inch fasteners both have the same tensile strength.
- A2 refers to metric 18-8.
- A4 refers to metric 316.
- Class 50, 70 and 80 designate increasingly higher metric strength levels.
- A manufacturer’s mark is required on metric M5 or larger diameters.