It can be used as a portable door lock or extra door lock as needed. Unlike other portable door locks, this product features a lockable design that can add an additional lock to the door, which can not only block the door but also prevent someone opening the door from inside or outside. Preventing unauthorized entry. Prevent children from sneaking out and elderly dementia patients from wandering out. For doors that open outward, you can also use this product to add an extra lock to the door when going out.