Stress Distribution: By providing a wider transition area, Type B undercuts help distribute mechanical loads more evenly, reducing the risk of "notch effect" failures.

The Width (g1 and g2): For Type B, the width of the groove is significantly larger than Type A. This extra width is often required when the manufacturing process involves grinding or when the fastener needs to accommodate a larger radius on the mating part.

The DIN 76-B undercut is a staple of robust mechanical design. By providing ample clearance and reducing stress peaks, it ensures that threaded assemblies remain secure and functional under load. For any designer or machinist working with ISO metric threads, adhering to these dimensions is non-negotiable for professional-grade manufacturing.