In fact, it’s very simple. double-opened gift boxes have one thing in common, that is, the box itself is very, very difficult to ensure that the box is closed only by the friction between the inner and outer boxes or the mounting of the upper and lower boxes, because of the double-opening feature, will make the box contact area is not like ordinary cartons, even if you pick up the outer box vertically, the inner box will not fall out, in order to ensure that the use of the double-open box when the flow is not hindered, will be relatively wide, do wide will bring a more difficult to rely on the box itself to overcome the difficulties, double open box is not closed tightly.