It works on a similar principle to that of Michael Brook's Infinite Guitar, and can be considered a commercial version of such. It is not the first such attempt, and its main commercial rival is the Sustainiac, used on many Hamer electric guitars, such as the Chaparral, Diablo and Californian superstrats, as well on most Jackson electrics such as the Phil Collen signature PC-1 and other various Soloist and Dinky models.
When activated, the note from a standard guitar pickup is amplified and fed back into a separate pickup coil. When this additional impulse is in phase with the string vibration, the result is a continuous sustained note.
Both the Sustainer and Sustainiac infinite-sustain devices feature a special-design humbucking pickup usually placed in the neck position and two mini-toggle selector switches for mode selection (fundamental, harmonic and blend). The whole system is driven by an active on-board circuit with a 9V (or 18V) power supply.