Subsonic 3.0 UPDATE, multiple conditions

      db.Update<Luna.Record.TB_ITEM>().Set(
                x => x.ITEM_DURABILITY == Convert.ToInt32(quantity))
                .Where(x => x.ITEM_POSITION == Convert.ToInt32(position))
                .Execute();

How will I add an AND clause this is how it looks like in plain SQL:

UPDATE TB_ITEM
SET ITEM_DURABITLITY=@quantity
WHERE ITEM_POSITION=@position AND CHARACTER_IDX=@charidx

.Where(x => x.ITEM_POSITION == Convert.ToInt32(position)
            && x.CHARACTER_IDX == Convert.ToInt32(charidx))