Contains user profile data for Mozilla programs such as Firefox and Thunderbird; may include bookmarks, browsing history, and cached data; typically saved with a random filename, followed by the ".slt" extension.

In Windows Vista, the Firefox SLT folder is saved in the "Users\Profile\AppData\Roaming\Mozilla\Firefox\Profiles" directory. In Mac OS X, it is located in the "~/Library/Mozilla/Profiles/[profile name]/" directory.