Wow, this is a really amazing add on. It is like a combination of One Tab and Safari's Tab Group feature but surprisingly better than both in most ways. It let's you make tab stash groups, name them, you can select tabs from each stash and add them to their own group or reopen the selected ones in a new group, and it adds the tab groups to a bookmarks folder.

Only things I'd love to see is the ability to pin a tab group since it's always pushing down groups as I stash. The bookmarks folder also can get pretty long, but it's nice that it can remember old links for so long. For a person constantly opening 30 tabs at once, the feature is a must-have for Firefox and replaced several add-ons I had previously.