This is a quote from - http://www.ubnt.com/sr5_faq.php4
A: Because the SR2 card was the first of its kind, there were programming changes made shortly after its introduction which improved operation with the MAD WiFi driver and other operating systems employing it. All SR2 stock available for sale today through any of our authorized resellers will be the current programming.
My question is how can we tell if we got the good version?