The date code for the Intel® Dual Band Wireless-AC 7260 can be found on the bottom line in the back face of the adapter:
This information is displayed in the WW YY format, that is work week, space, year:
Adapter on the left: 25 13 = June 2013.
Adapter on the right: 09 13 = March 2013.
Please let us know if this is the information that you're looking for. Otherwise, please let us know which date code you're referring to, and for what purpose you will be using the information.