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By certification 
The strength grade of the high-strength bolt is grade 12.9, that is, the tensile strength is above 1200 MPa, and the yield strength is above 1080 MPa.
The material is 40Cr, 42crmo, and the surface treatment is black. Mainly for textile, hydraulic, injection molding, machinery industry in use.
http://www.maitongfastener.com/
