The primary function of DIN 7161 is to define tolerance classes based on nominal dimension ranges.
If you are seeking a PDF version of DIN 7161, "extra quality" refers to the of the document: din 7161 pdf extra quality
DIN 7161 is a German standard (Deutsches Institut für Normung) that defines the quality requirements for cylindrical and tapered rollers used in various applications, including bearings, gearboxes, and other mechanical systems. The standard covers the dimensions, tolerances, and surface finish of rollers, ensuring their interchangeability and compatibility with other components. The primary function of DIN 7161 is to