Boeing and Air China have announced an order for 6 additional 777-300ER jetliners. The order is valued at more than $2 billion at current list prices and bolsters Air China’s long-haul widebody fleet as it looks to expand its international network.

China’s flag carrier continues to modernize its long-haul fleet to replace aging aircraft and plans to expand its growing network internationally.

Air China currently operates a fleet 174 Boeing airplanes, including nearly all current Boeing production models, including the Next-Generation 737, 747-8 Intercontinental as well as 777-300ERs.

With this new order, Air China will increase its unfilled airplane orders with Boeing to 90 units, which include orders for new 787-9 Dreamliners.

The 777-300ER is one of the most fuel and cost-efficient airplanes in its class as well as the most reliable twin-aisle aircraft in the world.

It also has the highest cargo capability of any passenger airplane in service. The 777-300ER will receive further improvements in 2016 designed to reduce fuel use by another 2%.