other shapes such as rectangular teeth triangular shaped teeth etc matched to the specific embodiment of the shutter likewise other simple guide mechanisms may be used in place of a plastic strip 102 to prevent engagement of the teeth when no large load is present according to this embodiment the loads against the slats from wind impact etc forces the slats into a shaped track that passively u2018 latches u2019 or retains the track against vertical movement until that load is removed at which time the shutter is again free to be retracted as used herein the term u201c slat length u201d refers a distance between slat ends i e the distance across the opening covered by the shutter plus additional allowance for track engagement etc the slat height refers to the distance from a bottom surface to a top surface of an individual slat a reference to u201c horizontal u201d herein refers to a horizontal direction when viewing the slats from a front surface of the shutter curtain it is noted that compressive loading of the shutter is not required it is not necessary to deploy the shutter array using a tractor mechanism to vertically load the shutter curtain the shutter may simply hang free from an upper region of the protected opening and rest against a surface below a bottom region of the opening thus when in position to protect the opening the primary upward forces exerted on the shutter are those supplied at the upper region for example as exerted by the wind up wind down mechanism while the invention has been described with reference to preferred embodiments it will be understood by.