Fenster Keller is a Swiss company specializing in the production of high-quality windows and doors. Based in Bütschwil, St. Gallen, they offer a range of products, including wood, wood-metal, and sliding windows, as well as custom-made solutions for various architectural needs. Known for their Swiss craftsmanship, they combine traditional techniques with modern technology to ensure precision and durability. Fenster Keller AG also provides professional installation and maintenance services.