They’re wireless receivers, one for my mouse and one for my wireless modmic.

Both would probably work okay hidden out of sight, but I had issues with the mic (that turned out to be a part of a recall, so not a problem anymore) so I’ve had the dongle out here for a while, and it is nice to be able to visually see if I’m hardware muted. The mouse is similar - nice to be able to unplug the dongle and have a wired mouse temporarily to charge it.