Understanding Metric Bolt Grades
Metric steel fasteners are often identified by a property class such as 8.8, 10.9 or 12.9. These markings relate to mechanical-property requirements defined by applicable standards; they should not be treated as a substitute for a project specification.
Why the grade matters
The requested property class affects strength and suitability. A higher number is not automatically “better” for every application because the mating parts, loading, environment and design specification also matter.
When requesting a quotation
Where possible, provide the full description: fastener type, metric size, length, property class, standard, finish, quantity and any certification requirement.
This guide is general purchasing information, not engineering design advice. Confirm critical applications against the applicable project specification and standard.