Many types of Asian pipes are mistaken for opium pipes, but there is only one true opium pipe: one that was designed to vaporize the drug, not burn it. This was achieved by the means of a highly specialized pipe-bowl. The bowl, which actually looks nothing like a traditional bowl but rather like a door knob, was attached to a long stem by means of a metal fitting, referred to in English as a "saddle". The length of an opium pipe varied from approximately 15 inches (40cm) to about 22 inches (56cm). The most common material from which pipe stems were made was bamboo, but Chinese artisans experimented with myriad substitutes, including ivory, jade, horn, porcelain, as well as enamels such as cloisonne. The result was often a striking work of art.