United Airlines revealed more details Tuesday about its new basic economy fare, which promises the cheapest seat on the plane if passengers are willing to give up things such as pre-assigned seats and overhead bin space.

The new type of fare is the latest strategy for major U.S. airlines to compete with budget carriers like Spirit or Frontier airlines, which have pioneered the unbundled model by offering low base fares and additional fees for extra services.

Delta Air Lines has already introduced its basic economy product, while American Airlines has its own version in the works for next year.

United executives on Tuesday framed the new type of fare as a way to target customers “whose ideal flight means greater choice and lower price.”

“There’s no one-size-fits-all passenger. There shouldn’t be a one-size-fits-all flight,” United CEO Oscar Munoz said in a video announcing the new offering.

But while airline executives tout the flexibility and customization offered by these no-frills fares, for customers it might feel like a continued erosion of the minimum standard for air travel.

United’s basic economy product guarantees customers a seat on the plane and little else.

Seats are assigned at check-in, meaning those traveling in groups might not be next to each other. The fares include no ticket changes and no upgrade eligibility, and basic economy passengers will board the plane last.

Members of United’s frequent flier program who purchase basic economy fares will still earn award miles, but not elite status qualifying miles or dollars.

The most surprising move is United’s decision to limit basic economy passengers to a single personal item that must be stowed beneath the seat, meaning no carry-on bags can be stowed in the overhead bins. United travelers with Premier status or a qualifying co-branded credit card will still be allowed full-size carry-on bags.

“That decision to not include full size carry on bags I think is the gutsiest move and the one that frankly, I think, sets the United basic economy fare apart,” said Henry Harteveldt, a travel industry analyst and founder of Atmosphere Research Group. “When you introduce a product like this, you want it to be attractive enough to bring in new customers, but unattractive enough that existing customers don’t trade down.”

Delta’s basic economy product closely mirrors United’s, except the Atlanta-based carrier is still allowing carry-on bags. American hasn’t revealed details of its own offering yet, but it probably won’t differ much from its competitors.

United’s basic economy fares will go on sale early next year on select routes, the company said.

How much customers actually will save is still unclear. United didn’t offer details on how the basic economy fares will be priced, but Delta’s similar offering is typically $10 to $20 less than its standard economy fare, Harteveldt said.

“Will it be at least $25 less expensive? Because all of a sudden the traveler’s going to have to think about checking a bag,” Harteveldt said of United’s plan. “The cheapest fare is not always the best value for a traveler. If you’re traveling with a family, you will probably not be seated together.”