Below is a list of Door Latches manufacturers from St. Louis, Missouri. Door latches are a type of mechanical hardware used to fasten doors and keep them shut. A door latch uses a fastener attached to two ordinarily separated surfaces, most often the door and the frame, to prevent the door from swinging while still allowing normal operation when the latch is released. Though latches have traditionally worked in conjunction with locking mechanisms, recent latches combine both latch and lock into one piece of hardware.