922-9131 Mechanism Cover - 21.5 inch Late 2009 A1311 3.06-3.33GHz iMac NB-3155W Apple part number: 922-9131, Compatible models: A1311-Late 2009-MB950LL-MC413LL,, Compatible Mac info. : 21.5-inch 3.06GHz iMac, 922-9131 Mechanism Cover - 21.5 inch Late 2009 A1311 3.06-3.33GHz iMac Apple part number: 922-9131