The "1:1" icon is added automatically.

When clicked for the first time (or then when double-clicked), it will prompt you to zoom your object manually to a known true size.

Then it will use the same zoom ratio automatically.

It is intended to be used for orthographic views of your design files.

Install:
1. Download the installer from the Autodesk App Store.
2. Right-click on the "Downloads" folder and select "Open in Finder".
3. Right-click on the "View11_macos.pkg" -> "Open With" -> "Installer".

Uninstall:
You can unload the add-in without uninstalling it by clicking the "Stop" button when the add-in is selected in the list box on the "Add-Ins" tab of the "Scripts and Add-Ins" dialog.
Unchecking "Run on Startup" causes the add-in not to be loaded in future sessions of Fusion.
- Navigate to the ./ApplicationsPlugins folder and select the app bundle you want to uninstall
- Either drag the app bundle to the Trash or right-click and select “Move to Trash”
- Right-click on the Trash-Can and select “Empty Trash”
- If you prefer keystrokes, you can also just select the app bundle and then hit Command+Delete to move the app to Trash, then empty the Trash and the app will be removed.

License: View11 is a freeware version of a utility by ARKANCE (includes Python code).