Guitar vibrato bridge and locking nut by Floyd Rose (Floyd Rose Tremolo System). System main parts are floating bridge with vibrato arm and springs and locking nut.  Floyd Rose has been in markets many decades and has gained initial popularity through famous guitar players like Eddie Van Halen, Neal Schon, Joe Satriani and many more. 

It has excellent tuning stability via the double-locking design: This makes the guitar stay in tune through large pitch changes, e.g. forcing the vibrato bar all the way down or pulling up on the bar to raise the tone. In V25-series tremolo guitars bridge spring adjustment is made very easy; no back cover opening needed. Only hex key needed and that comes with the guitar.