This extension is only needed for the App Store version of TrashMe 3.
Due to Apple rules for apps distributed on the Mac App Store, TrashMe 3 has some restrictions: files requiring your password need to be trashed manually and the maintenance section is hidden by default.
With this extension, the Maintenance section will be restored and you’ll be able to delete all files when uninstalling apps or cleaning your Mac.
The extension will install some scripts into the folder ~/Library/Application Scripts/ (same scripts than in the non-Mac App Store version). You can uninstall these scripts thanks to the same installer downloaded above.