Delta Air Lines has agreed to a firm order for 100 Airbus A321neo jets.

The airline also agreed to an option for an additional 100 A321neos.

The total value of the 200 aircraft is $25.4 billion at list prices.

Delta Air Lines announced a firm order for 100 Airbus A321neo airliners on Thursday with a list value of $12.7 billion. (Neo stands for new engine option.)

The Atlanta-based carrier also agreed to an option for 100 addition A321neo jets. Including options, the deal could potentially be worth up to $25.4 billion.

However, it is an industry norm for airlines to receive major discounts on bulk orders such as the one placed by Delta.

Delta also announced that Connecticut-based Pratt & Whitney's ultra-fuel-efficient next-generation geared-turbofan engine will power the 100 planes.

"This is the right transaction at the right time for our customers, our employees, and our shareholders," Delta CEO, Ed Bastian said in a statement. "Delta, Airbus, and Pratt & Whitney share the same commitment to safety, efficiency, innovation and continuously improving the customer experience."

The aircraft will be used to replace Delta's aging fleet of McDonnell-Douglas jets that has served as the airline's workhouse for several decades.

According to Airbus, a significant number of the mega order will be produced at the manufacturer's plant in Mobile, Alabama with deliveries starting in early 2020 and ending in 2023.

Delta's A321neo's will have 197 seats, on-demand in-flight entertainment, high-speed satellite-based wifi, and overhead bins with 25% more space.

"The A321neo will equip Delta employees with a customer-preferred, versatile narrowbody aircraft befitting their position as a global airline leader — and we are excited to continue to partner with them as they deliver industry-leading operational performance, customer satisfaction, and financial results," Airbus Commercial Aircraft COO John Leahy said in a statement. "In addition, our workforce at the U.S. Manufacturing Facility in Mobile, Alabama is proud that they will be delivering many of these A321neos to Delta in the coming years."

The Delta order is expected to be the final mega-deal brokered by Airbus' legendary sales chief before his retirement at the end of the year.

This is just the latest in a series of orders Delta has placed with Airbus in recent years. The second largest airline in the world has ordered more than 130 current generation A321ceo jets along with major tranches of A330neo and A350XWB wide-body jets. (Ce0 stands for current engine option.)

Boeing's 737-MAX10 was also believed to be under consideration. But, a recent trade dispute triggered by a complaint filed by Boeing concerning Delta's order for 75 Bombardier C Series jets has soured the relationship between airline and airplane maker.