The barrel is 16" with a 5.56NATO chamber, chrome-moly vanadium, mid-length gas system, pinned front sight base, 1:7" twist, and black nitride finish.
It is a complete upper assembly with bcg and charging handle. It is brand new and never fired, only taken out of the box for inspection and pictures.
These are listed for $640 on their website without the carry handle (https://www.aeroprecisionusa.com/ar15-556-16-complete-upper-fsb-mid-bcg-ch) and I recently saw someone else's Easter sale listing it at $575, I'm asking $400 obo.