This rod spans a 100 inch wall opening for a bedroom bay window in our typical 100+ year old Toronto gable-and-bay style semi, with 10 inches on either end to insure good light blockage.  We are pleased that the shallow rod does in fact block more light than conventional rods.  The blackout curtains are very heavy and with the middle rod support, there is great stability.  As always with Umbra products, the design is as striking as it is functional.  Installation was a simple matter of measuring, marking, and drilling as per the very clear instructions.  Great value for the money.