Save Ext.
Save Extensions defaults to Acekard's standard ".nds.sav" extension. For compatibility it is recommended to use ".sav", which is standard amongst other flash carts. If you have existing .nds.sav files, you can highlight them and select their "Properties" to enable the "Save Extension" button. This button will convert all ".nds.sav" files (including save slots) to ".sav" (and vice-versa) for the title selected, assuming you set the AKAIO save property option to .sav. Options are .nds.sav and .sav.