Abstract: A flexible, rubber-like member in the shape of a flat "dumbbell" has a pair of holes at either enlarged end thereof for fitment respectively about the opposed knobs or handles of a door with the narrow portion thereof wrapping around the side edge of the door proximal the knobs to prevent closure of the door. In an alternatively preferred embodiment, there is provided a signal generating mechanism for indicating when an attempt is being made to close the door with which it is being used.