United started selling seats in so-called premium economy class on Monday. Travelers willing to pay more than the regular coach-class fare will get bigger seats with deeper reclines than those in regular economy, amenity kits, free alcoholic beverages and noise-reducing headphones, among other perks.

Don't want to shell out $7,000 for business class but fretting spending a 16-hour flight crammed in coach? United Airlines is rolling out a new class of service for travelers looking for something between the two extremes on some of its longest international flights.

Other airlines around the world — including United's closest competitors at home, American Airlines and Delta Air Lines — already offer a version of premium economy and are in the process of expanding it to more aircraft. It is part of airlines' efforts to slice their cabins into new sections to encourage passengers to pay higher fares to avoid the skimpiest services.

The price of a ticket aboard United's version varies depending on the route and demand, but an April 12-19, 2019, trip from Newark to Hong Kong showed up as $1,071, while a seat in premium economy was close to $3,660. Business class for the same route was $7,050.

United said the premium economy class, which it is calling "Premium Plus," will be on 21 international routes by May and service will begin on some international flights starting on March 30, 2019.