100% Room darkening!! They are a very good quality, nice and thick. Has a bit of a sateen shine to them but nothing overpowering. We bought them because my husband works overnight so a dark room was a must. These curtains are so dark, I keep accidentally sleeping in because I think its still nightime!! We got the charcoal color and love them so much! These will also definitely help during the winter to keep the cold from coming in through the windows! Still need to steam them to remove the wrinkles. Thick and heavy. Def reccommend!