VELUX FCM fixed curb mount skylights are ideal for replacing existing curb mount skylights, including old plastic bubble skylights. It can be installed on a flat roof at 0 up to a 60 roof pitch on a site-built curb. VELUX skylights are an energy-efficient way to bring sunlight into a home and make dark rooms come to life, all while maintaining privacy. Installing a skylight is one of the most impactful ways to enhance the brightness and beauty of a room.