In September 2005, Nintendo re-released the Game Boy Advance SP with an improved backlit screen and a model number of AGS-101 (vs. the original frontlit version with model number AGS-001). The button that turned the light on and off on the original model instead switched the brightness between low and high and provided no ability to turn the light off on the new model. Even on low though, the brightness of the new model exceeded that of the original.
Contributed by Petie