Tremolo Arm, Arm Design

Instruments without this device are called hard-tail . The term vibrola is also used by some guitar makers to describe their particular tremolo arm designs. The tremolo arm began as a mechanical device for more easily producing the vibrato effects that blues and jazz guitarists had long produced on arch top guitars by manipulating the tailpiece with their picking hand. However, it has also made many sounds possible that could not be produced by the old technique, such as the 1980s-era shred guitar "dive bombing" effect. It may also be used outside it's socket for different effects, as in Whammy Tapping.

Throughout the 1960s, the premium Fender guitars were the Jaguar range, equipped with the floating tremolo . By the early 1970s, it was obvious that most guitarists preferred the cheaper Stratocaster, regardless of price and supposed quality and prestige, and particularly liked its tremolo arm design. The Jaguar and indeed all other Fender guitars using any tremolo design other than the synchronised tremolo were for a time withdrawn, to return to the catalog as classic or retro models in the 1990s.

This was simply known as the Fender vibrato tailpiece , or sometimes the Fender steel vibrato . It was again designed by Leo Fender although he had sold the company by the time it appeared. Basically a synchronized tremolo simplified to reduce cost, it had little popularity, and was the only Leo Fender tremolo arm design not available on any current Fender model.

Source: Wikipedia > Tremolo Arm