Louvers are horizontally running slats that are in a window or framed opening. A popular application for a louver is at a gable end, where ventilation into the attic is desired.
ROOF LOUVER PURPOSE
The purpose of a louver is to allow for ventilation while still protecting the inside from other elements such as blocking out rain, dirt or sunlight. Louvers often allow for the angle of the slats to be adjustable.