When the door is shut and the handle is moved into the closed position, not only are the locking mechanisms engaged, but the full weight of the vent is set down onto the frame. Intruders would not only need to create enough leverage to break the multi point locking mechanism, but also move the weight of the vent. Considering that vents on larger lift and slide doors are easily 100 to 200 kgs, it adds a significant amount of security.