The exterior venetian blinds, or stackable blinds, often require lateral guides to be stabilized against the wind. That often results in excessive carpentry thicknesses and rough rotation mechanisms on the head of each slat. In this case, a very simple and interesting design has been reached. Warm wooden slats are simply guided through a pair of metal stretchers, fixed to the lintel and the threshold. Simple metal sheet reinforcement ensures durability of the area of the slat that rubs against the stretcher.