External window shutter

An external window shutter for installation in front of a window opening of an external wall of a building, said shutter comprising:

• a frame enclosing said window opening and externally secured to said wall;
• a pair of coplanar panels mounting on said frame and defining a plane;
• first and second guide members attached to said panels and said frame, respectively, each of said first and second guide members having complementary first and second engager parts shaped to slidably engage each other for moving said panels along a path of travel, said first and second guide members being located on the a same side of said frame;
• said panels, when positioned together in a closed configuration, substantially enclose said frame;
• and
• a retaining mechanism carried by said frame and connecting to said panels to constantly retain said panels in a vertically oriented position, said retaining mechanism including:
• at least four coplanar supports positioned for enclosing said window opening, each of said supports mounting on said frame and including two coaxial pulleys independently freely rotating from each other and two cables meshing with a respective one of said two coaxial pulleys of each support to form first and second enclosures around said window opening, each of said enclosures being generally parallel to each other and defining upper and lower generally linear horizontal segments and two generally linear vertical side segments, one of said panels connecting to said upper and lower portions of said first and second enclosures, respectively, with the other one of said panels connecting to said upper and rower portions of said second and first enclosures, respectively.