Truly a max blackout effect, even in the white color, especially if you buy a longer set and hang so that the top of the panel is near the ceiling. I deducted a star because the length of the panels in the two sets I received are off by a couple of inches, so a couple of panels reach the floor while the other two don't even graze the floor. However, these are in a bedroom and I simply hung the two shorter panels at a window where the blottoms are visible and the longer two at a window with a desk obscuring the bottom of the curtains. Buyer beware if you are bothered by irregular lengths.