It’s a simple 3D head structure more primitive than most 3D heads, so it forces you to not just trace it. It helps demonstrate that the front of the face sits on a flat plane.
Use it to draw a face head-on. It helps you know where the eyes and other features naturally go. You can scale the head on various axes to make different head proportions.

Use it to draw a head at an angle. The front plane of the face helps you not put the eyes too close to the ears.

Material
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Default material
Allocate
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Default layout