School backpacks with a zipper

Zipper

— known to many as a "zipper", fastened and unfastened in one movement along the connection line. In addition to speed and convenience, the advantages of such locks are a tight connection — the parts of the backpack / satchel / bag are fastened along the entire line of contact, there are no noticeable slots or holes between them, and the likelihood that something will fall out from the inside or get inside from the outside is very small. The disadvantage of lightning can be called a relatively high probability of breakdowns, but this moment is noticeable only on the cheapest locks, whose manufacturers do not pay much attention to reliability.