and a thinner sound; the Conn is also lighter). Additional valves In the 1920s and 1930s, four-valved sousaphones were often used by professional players, especially E sousaphones; today, however, four-valved B sousaphones are uncommon and are prized by collectors, especially those made by Conn, King (H.N. White), and Holton. Jupiter Company started production of four-valve BB sousaphones in the late 2000s, and Dynasty USA makes a four-valve BB sousaphone as well. Criticisms of the fourth valve on a sousaphone center around additional weight, although the fourth valve improves intonation and facilitates playing of the lower register. Due to the large size of most sousaphones, the sub-contra register (for which the fourth valve is largely intended) is already covered by alternate resonances, known as "false tones" (see Tuba article). Many beginners are not aware of the false-tone resonances on their sousaphones because these notes reside in the sub-contra register, which is nearly impossible for most beginners to access. Some professionals develop a "raised embouchure" to securely play these notes. This is where either the upper or lower lip (depending on the player) takes up most of the mouthpiece area. The embouchure provides almost twice the room for vibration of the single lip (compared to the 50–50 embouchure). Non-American sousaphones Asian sousaphones made in China and India are gaining popularity in the street band market. In Switzerland and Southern Germany, "Guggenmusik" bands often use these instruments that provide great display and passable tone. Most are tuned in E. Brands like Zweiss with older British designs make affordable sousaphones that have broken the €500 barrier. These are mostly in the medium-bell size of . Chinese brands are mostly reverse-engineered models and quite passable. Special effects In large marching bands of the United States, the bell is often covered with a tight fitting cloth, called a sock, which enables the sousaphone section to spell out the school's name, initials, or mascot. The Leland Stanford Junior University Marching Band Tööbz! have a tradition of painting the front surface of their sousaphone bells with a variety of images. Sousaphone players are also known to perform the 'flaming tubas' in which flash paper is ignited in the bell, thus making it appear as if the musician is breathing fire. David Silverman developed a propane powered flaming sousaphone with a trigger valve to control an array of flame jets across the top of the bell of his horn.