The available selection for the limited-time special includes the Quarter Pounder with Cheese, Big Mac, Filet-O-Fish, and 10-piece Chicken McNuggets.
The selection is the same as the two-for-$5 mix-and-match deal offered earlier this year. You can basically view this as the same deal but with a slightly different cost structure that probably more friendly to franchisees in areas with higher costs (for example, here in Southern California where it's pricier, a Big Mac is $4.79 so it would be $5.79 for two Big Macs under the deal).
Photo via McDonald's.