No idea how much they cost but it is an electronic hydrometer
http://www.densityanalytics.com/index.htm
I’d be kicking myself in the arse if I broke that one! >:( 
It looks expensive! Me and expensive don’t normally get along. ;D
That would be really cool to just sanitize and drop it into the fermenter and have real time measuring of the gravity. But yeah, I’m sure it’s really expensive.
even cooler would be a remote probe (wireless) that could beam the info up to your computer software!
Inevitably I would dump the sensor out with the trub in the fermenter! Instant read outs of the gravity of my compost pile!
Yeah like I put my stir bar into the fermenter without fail ;D