Processing good fit disappointing

Visually beautiful designter helmet from China, and with 41 Euro totally favorable.
Extent of rotary ring and Y-strap can be easily adjusted, ventilation is more than adequate, and the supplied cloth bag protects the helmet during transport. In addition, a support system for headlamps integrated.

Only the fit to complain (I otherwise helmet size ~ 56 cm).
Since the holding system, va is striking not deep-drawn in the forehead down, the helmet can be much easy to strip from the head.
He likes the seat while acting convenient because the helmet is held seemingly well on his head from the Y-belt, and therefore will not be tightened up, but really sit sure he does not with me.