The listing, TEKCASE FOR DS LITE WITH BUILT IN EXTRA BATTERY has ended.
This is made for the DS LITE. It more than doubles your play time with the built in battery while protecting your DS Lite. I have one on mine and if the battery runs low simply flip the little switch and you have more power. Up to 2 1/2 what the normal battery provides. BNIP, never opened. Comes with charger and instructions.