Irish low-cost carrier Ryanair has signed an agreement with Boeing to purchase 175 737-800s valued at $15.6 billion at list prices.

Ryanair’s shareholders must still approve the order before it is finalized. The carrier said around 75 of the 737-800s will be used to replace existing aircraft in its fleet of 305 737s, while the rest will be used for growth. CEO Michael O’Leary said the order will enable Ryanair’s fleet to grow to more than 400 aircraft, all 737s, by March 2019.

While all of the aircraft in the order agreement are 737-800s, Ryanair said in a statement that “it continues to evaluate the benefits of Boeing’s 737 MAX aircraft, which enters service in 2017.”

O’Leary said the 737-800s will “provide Ryanair with the additional capacity to exploit substantial growth opportunities that currently exist as many of Europe’s flag carrier and smaller airlines are restructuring and reducing their short-haul operations.”