Unfortunately it is not a "G3" which I guess is the third generation of this thing. I found one on Ebay that looks like mine for $400 so still good. I didn't want to make this a "yo found this, how much is it worth?" kind of thread but at the same time that is basically what I'm doing because I have no idea what it's for. I just saw Sennheiser and knew to keep it lol. More info: it has a blue display and has 518-560 MHz for frequency range.
I think it's part of a stage monitor system. It's meant to broadcast a wireless signal, the frequency is for choosing the channels (like you would on a shortwave radio) to that receiver (the plainer box) so the musician can hear the rest of the band. Alternately, the plain box could be the the one broadcasting a signal from a wireless mic, that's why the bigger box has an earphone output port. Kind of like what you can see hanging on her right hip here:
As if I know this photo is a good example (found it on Google real quick) because I was looking at the gear.
Then again, I can't see her ears or other side of her hip, so she might have both. In any case, does the box with the display have any inputs on it? And are there any antennae ports on both? Is there a phono port on the plain box? Although chances are it won't be labelled as input or output, but if they're designed to work together, the bigger box having an input might mean it's for the stage monitors. Alternately it could work both ways so check for any switches, those would be labelled. Oh, and test throw away earphones with that thing until you're sure the plain box
is the receiver. It does say "IEM" on the plain box but I'd rather be sure first.
Still, why would you pounce on that with $400? You've been watching too much Storage Wars or Luggage Battles?
Well, in case it is for the stage monitors, congratulations - you just spent $400 on a hi-fi wireless system. Now if you can shell out another $100 or so, do tell us all if it's markedly better than $100 wireless transmitter-receiver+HPamp devices (I have one but I can't find it, won it in a raffle at a local meet). If it is I'm gonna start going through the pro-audio boards and feel all pro when I walk around with an ASG-1 and something like that
All my friends are too old school or too poor, they still use the floor-mount monitor speaker systems. Heck, I've never used a wireless mic my entire life - I just followed the drum beat to know when to start singing.