Shure was founded by Sidney N. Shure in 1925 as \"The Shure Radio Company\", selling radio parts kits several years after completely manufactured radios became commercially available. The company\'s office was located at 19 South Wells Street in downtown Chicago, Illinois. The following year, Shure published its first direct mail catalog, which was one of only six radio parts catalogs in the United States at the time. By 1928, the company had grown to over 75 employees, and Sidney\'s brother, Samuel J. Shure, joined the company, which was renamed Shure Brothers Company. The company moved into new offices at 335 West Madison Street in Chicago. In 1929, with the advent of the Great Depression and the increased availability of factory-built radios, Shure Brothers Company was forced to greatly reduce their staff and became the exclusive US distributor of a small microphone manufacturer.[specify] In 1930, Samuel J. Shure left the company. In 1931, Shure and engineer Ralph Glover began development of the first Shure microphone, and the following year, the Model 33N Two-Button Carbon Microphone was introduced, making Shure one of only four microphone manufacturers in the U.S. Shure\'s first condenser microphone, crystal microphone, and microphone suspension support system (for which they received their first patent) were all introduced that same decade. In 1939, Shure introduced the Model 55 Unidyne Microphone, which went on to become one of the world\'s most recognized microphones. In 1941, Shure was contracted by the United States armed forces to supply microphones during World War II, and by the following year, the T-17B was the microphone most widely used by the U.S. Army and Navy. Shure also manufactured throat, headset, and oxygen mask microphones, and adopted the United States Military Standard for all Shure microphones. By the mid-1940s, Shure was also manufacturing and supplying phonograph cartridges to major phonograph manufacturers including Philco, RCA, Emerson, Magnavox, Admiral, and Motorola, and was the largest producer of phonograph cartridges in the U.S. at that time. Among Shure\'s innovations in phonograph cartridge design was Ralph Glover and Ben Bauer\'s \"needle-tilt\" principle for minimizing record wear while improving sound reproduction, and Jim Kogen\'s engineering concept of \"trackability.\" Shure produced the first phonograph cartridge capable of playing both long-playing and 78 rpm records, the first cartridge with tracking force of only one gram, and the first cartridge meeting the requirements of stereo recording. At the peak of Shure\'s phonograph cartridge production, the company was producing approximately 28,000 cartridges per day, with 25,000 of those coming from a Shure phonograph cartridge plant in Phoenix, Arizona. After the introduction of compact discs in the 1980s reduced the demand for phonograph cartridges, Shure closed the Phoenix facility but continued manufacturing phonograph cartridges in Mexico.[2] In 2018, Shure announced that they would exit the phonograph cartridge market. [3] Shure also developed and produced products for medical applications. In 1937, their 66A piezoelectric stethophone was designed to accurately reproduce chest sounds, and in the early 1960s, the SP-5, SP-5S and SP-6 stethoscope pickups were produced. Shure also produced hearing aid cartridges used in hearing aid products from manufacturers like Maico, Telex, Dictograph, Otarian, Vocalite, and Trimm.