It is used to recharge the internal rechargeable battery or it can be used as a direct power source.
<br />
<br />Feature:
<br />100% new high quality Home AC Adapter for Nintendo DSi, DSi XL/LL, 3DS
<br />Ideal replacement / backup for original Nintendo DSi, DSi XL/LL, 3DS
<br />Featured foldaway prongs for easy carry and storage
<br />Standard US plug
<br />Automatically adjustable 100 - 240 V input fits World travellers
<br />Lightweight, small size
<br />Specifications:
<br />Input: AC 110   240 V   50/60Hz
<br />Output: DC 4.6 V   900mA
<br />Cord Length: 55in. (140cm)
<br />Quantity: 1
<br />Compatible with:
<br />Nintendo DSi, DSi LL/XL
<br />Nintendo 3DS
<br />Note: It will not work with Nintendo DS Lite
<br />
<br />In shipping package:
<br />1 x AC Adapter for NDSi/ NDSi LL/XL / 3DS