Does the job. Click on it to open last closed tab. That's all I need. Clean icon.

One button action, exactly what I needed since using middle click isn't possible anymore.

I give it one star as after I added this add-on to firefox, no button was installed. I looked every where but no luck. I installed and uninstalled it several times but never got a button for my toolbar…

It does what it said it would

Looks good.