UE FITS uses a TrueWireless Stereo pairing system. TrueWireless earbuds can use two different types of Bluetooth connections. Your UE FITS is going to connect using TrueWireless Stereo or TWS.
So what is TWS?
TWS is a connection style that uses one of your UE FITS earbuds as the primary connection between your media source and your second UE FITS earbud. Earbud one sends a signal to the source device, your phone for example, connects, and then forwards the same signal on to earbud two, providing an immersive surround-sound experience.
When you are initially getting paired your phone will pair to both earbuds first, so that you can use your left and right independently or together. From there, your UE FITS will pair dynamically to suit how you are using them.
The earbud that shows as connected in your devices Bluetooth settings is your primary earbud. The primary will get the signal from your phone and forward it to your secondary earbud. If you want to use just one earbud, simply place the earbud you are not using back in the charging case. You may hear a brief pause in your audio, if the earbud you put in the case was acting as the primary. Not to worry this is just your earbuds switching the primary to the earbud not in the case.