Air China has agreed to buy 31 Boeing aircraft, including 20 737-800s, according to a Friday filing with the Hong Kong stock exchange made by the airline.

In addition to the 737-800s, Air China said it has agreed to order two 747-8 Intercontinental aircraft, one 777-300ER and eight 777 freighters. The 777Fs will be used by Air China Cargo.

Under terms of the agreement with Boeing, Air China said it has the option to swap four 737-800s for one 777-300ER.

Boeing has not commented on the order.