Several embodiments of the shutters employ a variety of synergistic features which may be used individually or in combination to produce a shutter capable of more completely shutting out light. One aspect is the use of a two-step overlapping end to provide a complementary fit in order to shut out light. Another aspect is the use of an angled engagement pin which engages the louver not at its edge, but into its main expanse and nearer the center of pivot of each louver. Another aspect is the use of an accommodation space to accommodate the “U” shaped attachment member of the simultaneous actuation handle, which accommodation space can vary in size and depth to accommodate structures extending from the simultaneous actuation handle. Regardless of relative size, the louvers, engagement pins, and simultaneous actuation handle can be disciplined to form a neater appearance on the shutter assembly.