604-1542 604-0873 922-9143 Rear Housing - A1311 21.5 inch 3.06-3.33GHz Late 2009 iMac NB-3184W This is a replacement rear housing for the 21.5" iMac. This includes the stand and internal hinge mechanism. Apple part number: 922-9143, 604-1542, 604-0873