Boeing [NYSE:BA] and Ruili Airlines today announced the signing of a Memorandum of Understanding for 20 737 MAX airplanes at the 2017 Paris Air Show.

The airplanes, valued at approximately $2.2 billion at current list prices, will be posted to the Boeing Orders & Deliveries website once all contingencies are cleared.

"We are very excited about adding more 737 MAX airplanes to our fleet," said Xie Jinguo, General Manager, Ruili Airlines. "The 737 MAX's promised efficiency, reliability and passenger comfort make it a very compelling airplane for us in our domestic and regional network."

Launched in May 2014, Ruili Airlines operates a fleet of 14 Boeing 737 airplanes on 28 domestic routes with 76 daily departures. The start-up carrier plans to expand its fleet to 40 aircraft by the end of 2020.

"We have been impressed by the remarkable development of Ruili Airlines over the past three years," said Ihssane Mounir, senior vice president, Global Sales and Marketing, Boeing Commercial Airplanes. "We are honored to continue playing an important role in Ruili's long-term success with the addition of the 737 MAX. The airplanes will further strengthen Ruili's network by adding more domestic and regional routes in the years to come."

Today's agreement from Ruili Airlines continues the momentum of the 737 MAX in the marketplace.

The 737 MAX family has been designed to offer customers exceptional performance, flexibility and efficiency, with lower per-seat costs and an extended range that will open up new destinations in the single-aisle market.

The 737 MAX incorporates the latest technology CFM International LEAP-1B engines, Advanced Technology winglets, Boeing Sky Interior, large flight deck displays, and other improvements to deliver the highest efficiency, reliability and passenger comfort in the single-aisle market.

The 737 MAX is the fastest-selling airplane in Boeing history.