and the first to feature a flip-action built-in stylus guard. The V-15 Type IV (introduced in 1978) was the first to feature the dynamic stabilizer, which discharged static electricity from the groove and stabilized the cartridge for playback of warped records. The V-15 Type V marked the introduction of a proprietary "ultra-thin wall beryllium" stylus shank with a stiffness-to-mass ratio several times that of other cartridges on the market. In 1998, Sony Music Entertainment selected the Shure V15VxMR to transcribe 80 years of Columbia Records and Sony Music masters and recordings. In 2008, the British Gramophone magazine awarded the V-15 an "Audio Choice" designation for outstanding performance and value. Due to the scarcity of the raw materials required to manufacture V-15 cartridges, Shure discontinued the series in 2004, and in June 2009, the last remaining V-15 stock was purchased by the Library of Congress. On May 1, 2018, Shure publicly announced that they would be ceasing production of all phono products, effective Summer 2018. Sound reinforcement systems Shure introduced the Vocal Master sound reinforcement system, touted as "the first portable total sound system", at the 1968 winter NAMM Show. The Vocal Master system consisted of a combination of control consoles, speakers, amplifiers, mixers, and microphones. Multiple components and systems could be combined to expand the Vocal Master system to larger sound reinforcement applications. The Vocal Master was at one time the official on-tour sound system for performing acts such as the 5th Dimension and The Carpenters among others. Vocal Master was also utilized for installed sound applications in educational institutions and churches, as well as at the Rockefeller Center's Rainbow Room where it was used for performances by such artists as Benny Goodman and Duke Ellington, and at the London Palladium. Mixers and DSP In 1966, Shure introduced the M68, a portable mixer capable of being battery powered along with available accessories like a carry case and battery power supply specifically designed to address the needs of broadcast journalists and field recording personnel. The following year, the Shure M67 mixer added an illuminated VU meter and a line level output transformer for connecting the mixer to a telephone line. In August 1969, Eddie Kramer recorded the 4-day Woodstock Festival using three Shure M67 mixers. Shure's portable mixer line later included other models such as the M267 and 268. Shure introduced the FP31 mixer in 1983. The FP31 was smaller and