Using a unique biotechnology-based manufacturing process, we ferment the metal and create special bacteria that promote the aging process, creating the feel of a guitar that has been played for many years. This creates the world's first parts that "create the resonance and tone of an old guitar by applying an invisible, random, natural fermentation process (aging) to the metal parts." Introducing "sound aging parts" that create a vintage tone through realistic aging, rather than the look and feel of a relic or aged finish. The attack of the sound feels very vintage-like, with a particularly pronounced sense of dynamics in the choking and vibrato of each note. There's no excessive treble, and it produces a smooth, familiar attack. It gives the impression that the instrument being played is not a brand new one, but rather an instrument that has been played and is well-honed. Come experience this amazing sound. You can feel the effects even more when using it in conjunction with the separately sold tremolo spring (ZA-SP5) and neck joint plate (ZA-NBS3). ■Tremolo hanger (with 2 screws) *The individual item in the image is for illustrative purposes only.