Did not work for me, so I tried another one, "Yet Another Smooth Scrolling".
https://cup.aihedy.com/en-US/firefox/addon/yass-we

YASS at least works, but it really sucks compared to Smoothwheel. That was the best -- it was smoother than anything else, it had better controls, it worked on all web sites, and it worked with all mice (until Firefox Quantum broke compatibility.) Someone needs to resurrect this extension. I hate Firefox without it.

https://web.archive.org/web/20161123223319/https://cup.aihedy.com/en-US/firefox/addon/smoothwheel/

http://forums.mozillazine.org/viewtopic.php?f=38&t=3033273
http://smoothwheel.mozdev.org/

completely broken in Firefox - would give it negative stars if I could

Logitech tells me that it is 'something' on my system that makes it so their Logitech Setpoint software doesn't work in Firefox.

Thanks a lot Logitech.

P.S. This is why monopolies suck so bad!

.

The Logitech Smooth Scrolling ad-on had to be disabled as it prevented links in Thunderbird opening in Firefox. Windows 10 is OS.

Doesn't work, nothing changed AT ALL.
Firefox Quantum 60, Windows 8.1 64Bit

Doesn't work

Doesn't appear to work. FF 58.0.2, Windows 10, SetPoint 6.67.83, Logitech M705.

I'm changing what was a five star review to one star for one simple reason. The mice that require this extension are garbage and do not work properly in many programs, especially Metro apps in Windows 10. Do yourself a favor. Get a real mouse that doesn't need this crap. I'm still using a Logitech, but now one that does not need this extension. This mouse (it's a track ball actually) works FAR better and scrolls much more accurately than the one that needed this. A mouse should just work properly out of the box and not need special addons to work in certain programs. Ditch your cheap piece of junk mouse and get a real one, then you won't even need this stupid addon.

Doesn't work. Nothing changed after addon installation. Logitech T630, Firefox 57.0.2, Windows 10 1703, Setpoint software 6.67.83