Fits a roof pitch of 15&8211;90 degrees, PEFC-certified timber, sourced from well-managed forests, VELUX roof windows are best weatherproofed using VELUX window flashings, Double glazed with a u value of 1.4 (W/m 2K), Ventilation flap can be operated with the window closed, Requires less maintenence than natural pine finish, High quality moulded polyurethane with white lacquer finish & timber core, Forest friendly timber frame, High quality natural pine