Hiding skills of South Magnetic Box Extractor

There is no skill in this, it is purely a matter of luck.

A small part may have something to do with the weight of the box, but it is difficult to distinguish it because there is little difference.

Blind box refers to a kind of box whose outer packaging does not indicate the contents of the box. You don't know what's inside until you open it. Therefore, the blind box is full of unknowns and uncertainties, and many children and some adults will prefer it.