More than any other building material, Christoffel uPVC windows and doors keep their excellent material properties even after many years in use. As a matter of fact, they do not alter under extreme temperatures or weathering. Thanks to the uPVC profiles, they show no negative effects caused by heavy rain, snow, strong sun or smog. They do not rot, corrode nor warp even after many years, the windows are still attractive, perfectly tight and working well.