In the 20th century, modern versions of the "guan" were developed in China. These modernized "guan", which may be as long as a Western clarinet, have more tone and key holes and are fitted with metal keys to provide a wider and fully chromatic range. Such instruments are used primarily in large Chinese orchestras. These modern keyed "guanzi" are typically used for tenor and baritone ranges respectively. Although these "jiajian" (keyed) instruments are made of hardwood, their design originates from the houguan and their key system is related to clarinet's Boehm system with, typically with a short or no bell. While in theory these instruments can have a range as wide as the clarinet, they are generally considered to sound best in the lowest two octaves (due to the immense difficulty in controlling the Clarion register). In recent years, many models of traditional soprano Guanzi come fitted with one or more keys to improve the intonation of certain chromatic notes.