Specifications

Wi-Fi/Bluetooth Antennas
iMac (27-inch, Late 2012) has four (4) Wi-Fi/Bluetooth antennas. Three of which are removable.
The fourth resides inside the Apple logo in the rear housing assembly. It can only be replaced by replacing the rear housing.
Speaker Replacement
Speakers must be replaced in pairs. If you replace the right speaker you must replace the left one also. If you replace the left speaker you must
replace the right one also.
Push firmly to ensure the speaker sits down in the chin as far as possible. If the speaker isn't far enough down in the chin, it can cause display
interference issues.