Delta will add premium economy cabins to portions of its Boeing 767-300 and Airbus A330 fleets.
Retrofits will begin this month on 767s and will last through May of next year. A330 upgrades will begin in July and last through June.
According to the website SeatGuru, Delta currently offers Premium Select seating on Boeing 777s, Airbus A350s, Boeing 767-400s and Airbus A330-900neos.
The carrier said it will add Premium Select to 19 767-300s. Delta's 767-300 fleet currently comprises 37 in-service and parked aircraft, according to the website Planespotters.
Delta didn't specify how many A330s it will upgrade. The carrier has a total of 42 parked and in-service A330-200s and A330-300s in its fleet, Planespotters says.
Aircraft in both the 767-300 and A330 fleets will also receive additional upgrades, including refreshed lavatories, new LED cabin lighting, expanded personal power outlets and memory-foam comfort cushions, Delta said.