Years back when I got mine those were available from many of the usual online sources, I got it for around $20 from an online shop called “TomTop” (tomtop.com) but it’s no longer listed there.
It’s actually a clone of the Solarforce Gladiator. Recently I researched for the X-110 clone and wasn’t able to find it anywhere.
However the genuine Solarforce Gladiator appears to be still available here: https://www.solarforceflashlight-sales.com/products/solarforce-gladiator-professional-security-flashlight-body-with-3-dummy-18650-batteries-pouch
Unlike my clone the Solarforce uses a regular P60 Drop-in, so you can easily swap out the LED/driver with the many different versions that are widely available.
I also recently posted about these in my zoomie thread: Zooming Model List (2018 Updated) Tell us about your newest zoomie! - #168 by beam0
There’s also a thread here on a clone version from 2016 that includes a YouTube video: Know More about FX-X110 T6 900LM LED Flashlight ($16.14) via Hot Video