The key feature of the Linotype is the use of molds which circulate through the machine in its various stages of operation. One type is a space band (a special two-part sliding wedge) and the other is a letter matrix made of brass. The matrices are stored in one or more magazines on top of the machine (providing the operator with a choice of fonts; these can also be exchanged with other extra magazines as desired) while the space bands are stored in a box closer to the keyboard.