A skylight is a cold room window designed to provide ventilation and light for uninhabited and unheated loft spaces. For inhabited roof space you should really use a roof window.
Skylights are produced with 14 mm double glazed pane to improve insulation.
The skylight comes with integrated flashing so you do not need to buy a separate installation product. The flashing fits perfectly on tiles and slates too. After removing or trimming the foam gasket you can install the skylight perfectly on slates too.