Blockout – blocks out light and vision (Other than the gap around the outside)
Blockout fabrics are just that, blockout, no light comes through the fabric at all. However, because no light comes through the fabric it does accentuate the light coming in around the fabric and therefore doesn’t provide total darkness in the room, which may be an issue if you are light sensitive in the early morning. But they do give excellent privacy day and night.
Choosing which density really depends on what you want to achieve at what time of the day or night.
