The GF brand was officially registered in 1881. Since 1890, the company has used the + sign in its logo. This represents a stylized fitting, which is still among the most important products GF manufactures. Over all these years, the logo's font and appearance have been changed many times. In 2013, GF has implemented a rebranding and a alignment of its brand architecture. The most striking changes in GF's brand history are shown in the illustration below.