Macaroni is a variety of dry pasta made with durum wheat. Elbow macaroni noodles normally do not contain eggs, (although they may be an optional ingredient) and are normally cut in short, hollow shapes; however, the term refers not to the shape of the pasta, but to the kind of dough from which the noodle is made. Although home machines exist that can make macaroni shapes, macaroni is usually made commercially by large-scale extrusion. The curved shape is caused by the different speeds on either side of the pasta tube as it comes out of the machine. The name derives from Italian maccheroni, however Italians use maccheroni to refer to any form of pasta, whatever the shape, whether it is straight, tubular, two-inch or longer pasta. A different name, chifferi or lumaconi, refers to the elbow-shape pasta of this article.