It is indeed blackout/high shading (Greeks often mistakenly call semi-transparent curtains blackout; however, in this case, there is no mistake). It is white so a minimal amount of light passes through. If you want true blackout in white, it needs to be black on the back, but that way it increases the temperature in the area. It is very tall but small. That is, you need four and not two for a large balcony door.