A louver or louvre is a window blind or shutter with horizontal (or vertical) slats that are angled to admit light and air, but to keep out the rain and direct sunshine. The angle that the slats are positioned may and usually is adjustable, but it may be fixed too. Actually the elements are aluminum plates or galvanized with width of 100, 150 or 335 mm. The louvers may be arranged horizontally or vertically and may be fixed or movable with manual or automated actuation.
It is important periodic cleaning with a soft cloth and neutral detergent diluted with water. This product is under constant move so you need to be careful when you plan to clean them.