Systems Black out roller blinds from the Prosolar range are manufactured using fabrics that would completely block out the light from outside when the roller blind is fully drawn . Black out roller blinds are used extensively in conference rooms and meeting rooms to hold presentations using projectors . Prosolar black out blinds can also be used in homes where complete privacy is required . They have also found an innovative use in bathrooms with glass walls to enable the user to have complete privacy and also to enjoy the openness of the glass wall when desired .