This is a safety harness to prevent children from getting lost or being abducted. I used it only once while traveling because my child tends to run off. I was able to prevent my child from getting lost several times in crowded areas, so I was able to move around with peace of mind. It has a locking mechanism and comes with a key. For those who feel uncomfortable with a harness that attaches to the back, or for those with children close in age or multiple children, the wrist-worn type is easier to hold hands with. It seems possible to be about 2 meters apart. Please consider it.