Not bad for "blackout" curtains. A lot of light still comes through but for store-bought blackout curtains, they aren't bad. Maybe I'm just spoiled with the homemade blackout curtains I moved to my baby's room? I don't know that I'll buy the 3rd set I need to finish out my room or if I will keep looking.

Update: These are really hard to slide open and closed, even on a thin rod.