Recessed flashings provide a sleek and streamlined finish as the roof window is installed deeper into the roof structure, meaning that less of the roof window protrudes above the roofline. We recommend BDX insulation collar and BFX underfelt collar, included in EDN and EDJ 2000, for optimum energy efficiency. Recessed installation height - install the brackets at the sides of the roof window frame, at the blue line level.