Permanent Packers Types & Components
Permanent packers as the name implies are packers, when set, cannot be retrieved from the well. General characteristics common to permanent packers include:

- Permanently set. Once set, they cannot be released and retrieved from the well. A milling tool is required to remove a permanent packer from the well. The milling process will “mill over” the packer’s slips thus destroying them. The packer may then be pushed to the well’s bottom or retrieved to the surface.
https://www.drillingmanual.com/permanent-packers/