Firefox and HTTP HEAD method

Once upon a time, I had a plug-in in my firewalk that allowed me to make HEAD requests.
It looked like this: hold down the shift, move the cursor to the link and a small window with key information appears before your eyes. Most of the time I used it to specify the file size (well, the size is not always written).

I tried to find something similar now, but I did not find anything ... Strange.