As one of the leading experts for doors, the German manufacturer Groke Türen und Tore GmbH, based in Karlsruhe, fabricates high-quality aluminium main doors with modern and timeless design. All the while, customers can choose the design very flexibly using an online configurator. The Groke door design is classic and without unnecessary embellishments, geometric forms dominate. This is what makes the doors so timeless. Combined with the quality and the material’s features, the doors are long lasting and therefore a good investment and Aluminium is a great material for outdoor use as it is durable, weather-resistant, flexible and lightweight. When coming into contact with oxygen, aluminium naturally builds up an aluminium oxide layer of only a few nanometres, a natural protective barrier. If damaged, it rebuilds rather quickly.