593-1257 922-9217 Hard Drive Temp Sensor Cable, Digital - 21.5 inch 3.06-3.33GHz Late 2009 A1311 iMac NB-3097W This is a replacement hard drive temperature sensor for the 21.5-inch iMac. These are specific to the brand hard drive you are using. If you are replacing your hard drive, you may need to replace this as well if you are changing brands. Apple part number: 922-9217, 593-1257