Don't look now, but Boeing's (NYSE:BA) order book just got a little bit bigger.

On Thursday, the Seattle planemaker announced that Azerbaijani cargo airline Silk Way Airlines has ordered two 747-8 freighter aircraft, valued at $704 million together at list prices. SW Holding President Zaur Akhundov called the purchase a move toward making subsidiary Silk Way "a successful and profitable cargo operator... investing in its fleet and services and continuing to increase its regional and international footprint."

Silk Way's fleet is currently comprised of Boeing 747-400 and 767-300 freighters. Vice president for Middle East, Russia, and Central Asia Sales at Boeing Commercial Airplanes Marty Bentrott said in a statement that, "the 747-8 Freighter is the most efficient large freighter in the air and carries with it the 747 family's legacy of leadership in the air-cargo sector." 

So far, Boeing has delivered 36 747-8 freighters to customers around the globe.