Other World Computing OWCDIDIMACHDD09 Thermal Sensor for iMac Required for any drive installed into the main drive bay Fixes firmware incompatibility issues with third party hard drives Engineered in-house and backed by OWC's award-winning customer support Required for any drive installed into the main drive bay. Eliminate fan noise and maintain correct system fan control when upgrading your 2009- 2010 iMac. The only iMac HDD upgrade option on the market certified to pass the Apple Hardware Test. Fixes firmware incompatibility issues with third party hard drives. Engineered in-house and backed by OWC&#039;s award-winning customer support. iMac (27-inch Mid 2010)(July, 2010)<span class="a-text-bold">Model ID:</span>iMac11,3 (2.8GHz, 2.93GHz, 3.2GHz, 3.6GHz) iMac (21.5-inch Mid 2010)(July, 2010)<span class="a-text-bold">Model ID:</span>iMac11,2 (3.06GHz, 3.2GHz, 3.6GHz) iMac (27-inch Late 2009)(October, 2009)<span class="a-text-bold">Model ID:</span>iMac10,1; iMac11,1 (2.66GHz, 2.8GHz, 3.06GHz, 3.33GHz) iMac (21.5-inch Late 2009)(October, 2009)<span class="a-text-bold">Model ID:</span>iMac10,1 (3.06GHz, 3.33GHz)