Restored to former glory Heavy wood dimensions, solid rods, curved mouldings, outdated details and sash windows are rarely heard of these days, but these terms are still part of Bos’ everyday vocabulary. Nor would we be fazed by a request to make slanted windows for frames that are not right- angled. Using innovative techniques, Bos produces monumental sash windows with guides that are mounted on the position of the old weight pockets. These sash windows have a completely authentic appearance, but still comply with all modern insulation and safety requirements. This so-called Win Twin principle ensures an extremely supple and safe guiding of the sash window.