BS A 337:1999 Nuts, anchor, self-locking, floating, single lug, with counterbore, with MJ threads, classifications: 1100 MPa (at ambient temperature)/235 degreesC, 1100 MPa (at ambient temperature)/315 degreesC and 1100 MPa (at ambient temperature)/425 degreesC. Dimensions

standard by BSI Group, 02/15/1999