Abstract: A shutter is provided for attachment to window opening surfaces extending inward from a wall surface of a building. Mechanisms are provided to allow both the installation and removal of the shutter from outside the building. In a first version, a clamping mechanism feeds a bar into engagement with a surface of the window opening. The bar remains in engagement with this surface until a release mechanism is operated. In another version, a drive screw moves a compressible foot into and out of contact with the window opening surface. In yet another version, a toggle mechanism operates in such a way that increased engagement of an engagement surface increases the resistance to disengagement as the shutter is pulled away from the window.