Star-shaped (twelve-pointed) screw profile. It is known as a multi-tooth profile or XZN profile. XZN stands for ‘triple square’:

• The internal multi-tooth profile has twelve right-angled points. The cross-sectional shape can be formed by superimposing three squares of equal size, each rotated by 30°. This explains the English designation ‘Triple-Square’.

Why is the screw profile important?

• Choosing the correct profile
  • improves the fit within the screw head
  • reduces damage to the screw head
  • optimises force transmission
  • reduces slippage or damage

Wikipedia:

• The XZN profile is particularly common in the automotive industry, as it allows a relatively high torque to be transmitted to the bolts. A high tightening torque is required, for example, for cylinder head bolt assemblies. Due to the fine serrations and the slightly conical shape, dirt on the profile can make it difficult to insert the tool fully. Wear on the serration can (more so than with the coarser TORX® profile) cause the tool to slip, quickly rendering the screw head or drive unusable.
• [Wikipedia / Further explanation: https://de.wikipedia.org/wiki/XZN]

By the way:

• Here you’ll find an overview of common screw profiles

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