SFS Isofast Befestiger Stahl Durocoat IR2-M-4,8x80

The wrench sizes for hexagon bolts and nuts are specified in ISO 272: 1982-01. The nominal wrench size on the workpiece (e.g. bolt, nut) is the same as that on the tool. However, there is some play between the two to allow the tool to be fitted without difficulty. The relationship between the nominal diameter d of the thread and the wrench size s is standardised in EN ISO 4014 and EN ISO 4017 for hexagon bolts, and in EN ISO 4032 for hexagon nuts (dimensions in mm).

Case hardening is used to impart significantly greater hardness to the surface layer of steel workpieces and to improve their mechanical properties. Case-hardened workpieces are characterised by increased wear resistance, a tough core and improved fatigue strength.