SQLite database on SD card

I'm looking to create a sqlite database on the sd card (don't want to use up the user's internal storage). I'm familiar with the OpenHelper pattern:

public DatabaseFoo(Context context) {
    OpenHelper openHelper = new OpenHelper(context);
    mDb = openHelper.getWritableDatabase();
}

private static class OpenHelper extends SQLiteOpenHelper {
    public OpenHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    ...

so if we want to create on the sd card, I think instead we have to use:

public static SQLiteDatabase openOrCreateDatabase (String path, 
      SQLiteDatabase.CursorFactory factory);

But what is the "factory" argument supposed to be, what factory should be used?

Also a bit worried about what happens if the user removes the SD card while my app is in use..

Thanks