In short: EverTune is an all Mechanical bridge that uses a spring and a lever for each string to keep each string in tune once tuned. Each saddle pulls on each string with constant tension, naturally maintaining tune through all conditions, even changes in temperature, heavy bending and squeezing chords too hard. EverTune is well suited for the live environment, the recording studio and any time musicians want to put inspiration and playing above any thoughts about their guitars performance in any environment.
EverTune is a simple concept that keeps a string in tune until it wants to be changed. It is a very exciting development in stringed instrument technology. It is a passive, all mechanical system based on trigonometry and some rudimentary physics. Hence it is a new technology that is actually old school, its main component being a spring set in a clever position.
The benefits of this old school, all mechanical solution are that it is very rugged and reliable with only one moving part, and with all critical parts being made from high quality steel. It is also relatively reasonable in price, as opposed to servo-based (robotic) systems, and extremely effective.
It is distinct from servo-based (robotic) tuner systems: they automatically tune strings for the player, the player tunes the strings with EverTune, EverTune only keeps the strings in the exact tune set by the player.