Southwest Airlines said it agreed to buy 100 of Boeing's 737 Max 7 planes as it plans to retire older jets. The carrier said that under the agreement it would convert 70 of its firm orders for Max 8 planes to the smallest jets, the Max 7’s. It also added 155 options for 737 Max 7 or Max 8 airplanes through 2029. “This cost-effective order book with Boeing allows the company to maintain the operational efficiencies of an all-Boeing 737 fleet to support its low-cost, point-to-point route network,” Southwest said in a statement. The airline operates only Boeing 737 planes. The company continues to expect delivery of 28 Max 8 aircraft this year as well as 17 737-700 retirements, ending 2021 with 69 MAX 8 aircraft and 729 total aircraft. Mike Van de Ven, COO, said that in addition to supporting efforts to operate sustainably and efficiently, the 737 MAX offers employees and customers travel comforts such as a quieter cabin, larger overhead bin spaces, seating with adjustable headrests, and more galley space for onboard service.