Please Note: Removing and refitting the display on this range of iMac is not recommended without previous training or knowledge, as it is a difficult job to undertake. VHB strips are a very thin layer of foam between two self-adhesive plastic strips. A special tool with disposable cutting disks is used to cut the foam layer when removing the display and therefore this kit will be needed each time the display assembly is removed and refitted.
Please also Note: For iMac 4K models: strip completely covers the microphone and the holes in front of it which can deaden any sound picked up. Knowing this, the solution is simple. Make sure the microphone works properly before using any adhesive. Then, apply the adhesive strips, but when laying down the bottom strip, cut away the portion covering the microphone (and a little bit more from each side to be safe).