Before you begin, make sure you have the right adhesive strips:

The 2012-2015 iMac adhesive strips do not have a microphone cutout and are numbered 11, 12, 13, 14, 15, and 16.

Do not install these adhesives on iMacs newer than 2015. Without modifications, the adhesive will block the microphone hole.

If your strips are numbered 16, 21, 22, 23, 25, and 26, follow the 2012-2019 iMac adhesive guide instead.