From Wikipedia:
"After winning the International Fighter Aircraft competition in 1970, a program aimed at providing effective low-cost fighters to American allies, Northrop introduced the second-generation F-5E Tiger II in 1972. This upgrade included more powerful engines, higher fuel capacity, greater wing area and improved leading edge extensions for a better turn rate, optional air-to-air refueling, and improved avionics including air-to-air radar."
If I remember correctly the version we are getting won't have air-to-air refueling.
It is still a great quality module, though. It's pretty complete already. There is not much missing and it's very fun to fly.