Contour In Line VentsMarley contour in line tile vents are contoured to match the tile profile for all concrete interlocking tiles and concrete plain tiles, providing completely unobtrusive, almost invisible roof slope ventilation. They are ideal for roof designs where the normal airpath may be blocked or where it is not possible to provide normal eaves or ridge ventilation. They're easy and fast to install and can provide natural, mechanical or soil pipe ventilation.