iMac (Late 2012): VESA mount compatibility
iMac (21.5-inch, Late 2012) and iMac (27-inch, Late 2012) computers can be configured to order with a built-in VESA mount adapter when ordering via the Apple Online Store. The iMac with built-in VESA mount adapter lets you attach your iMac to a VESA-compliant mounting solution, such as an articulating arm or wall mount (sold separately).
VESA mount adapter upgrade kits are not available for iMacs with a stand. When an iMac is ordered with the built-in VESA mount adapter, the stand on the iMac is replaced with a VESA mount adapter and the iMac cannot be used with the standard iMac stand.