(NewsNation) — Several low-fare airlines now offer premium options, including priority check-in and more leg and elbowroom.

Spirit, Southwest and Frontier Airlines are among those introducing upsells that promise more comfort and convenience. The changes come as the industry faces disruptions from labor and parts shortages as well as scrutiny directed at plane manufacturer Boeing.

Frontier Airlines, which AirAdvisor named the most affordable airline in the United States, introduced its UpFront Plus model in March. It includes an upgraded seating option with more space in the first two rows. The option also offers a window or aisle seat with extra legroom and a guaranteed empty middle seat.

Spirit Airlines also rolled out four new travel options with no change or cancellation fees. The airline will additionally debut priority check-in on Aug. 27 for some customers.

Meanwhile, Southwest Airlines unveiled new enhancements in late July. In addition to introducing redeye flights and assigned seating, Southwest now offers premium seating in a portion of the cabin with extended legroom.

On a larger scale, the changes could mean passengers on a budget are bound to receive less desirable seating, but the upsells have been a financial success for some airlines. The recovery of post-pandemic air travel potentially encouraged customers to splurge on extra luxuries.

Delta Air Lines saw revenue from premium travel climb 10% in the first quarter, while Alaska Air said premium seating makes up 34% of its revenue, according to The Wall Street Journal.