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 implemented a rebranding and an alignment of its brand architecture. The most striking changes in GF's brand history are shown in the illustration below.