It’s an Ortho Remote, found here. It basically is a bluetooth HID device, that sends volume up/down commands when twisted and play-pause/next/back commands when single/double/triple clicked.
I have a few of them connected to the Mac mini that is running my core. For Roon, I use BetterTouchTool to caputure the commands (interpreted as keystrokes) and convert them into commands for @Ronald_Record’s excellent RoonCommandLine.
I also use a nifty Volume Control app for controlling Spotify as well as a collection of small Perl and Python scripts to control my KEF LSX (kefctl) and LS50 Wireless II (pykefcontrol) speakers directly.
Works great and is very flexible – you can hook up as many knobs as you like. My current count is seven. 
Any questions, just fire away – probably best in a different thread though.