While many plane passengers often confuse and use the terms “business class” and “first class” interchangeably, the latter refers to an even more premium level of service usually offered only by a few airlines on select flights.

For Middle Eastern carriers like Emirates and Etihad Airways, both fare classes come with lie-flat seats. But their first-class travelers get entire suites to themselves, on top of perks like like chauffeur service to the airport, waiters coming around with a selection of fine foods and wines, and generous baggage allowances and designer amenity kits.

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Another carrier known for ultra-luxury service, Singapore Airlines,  (SINGY) just announced that it was retrofitting seven of its Airbus A350-900  (EADSY)  planes to feature four first-class seats.

The investment of S$1.1 billion (US$835 million) also includes updating and reworking business class on a total of 34 long-haul A350 planes.

Singapore Airlines’ new first class

The flights on which first class will be available include what is currently the world’s longest flight: the airline’s 19-hour flight to Singapore from New York’s JFK.

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While the airline has disclosed few details about the new first class, and what it will offer that its current business class doesn’t, clearly the idea is an even more luxurious product.

“The new First Class and Business Class seat designs will incorporate thoughtful elements that push the boundaries of comfort, luxury, and modernity, allowing our customers to relax or work effortlessly on board,” Singapore Airlines CEO Goh Choon Phon said in a statement.

It is safe to assume that this will include more space in a suite-style design; the Singapore Airlines website already features First/Suites as a search option even if no such flights can currently be booked.

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Singapore Air CEO: ‘evolving preferences and expectations’

A business-class flight between New York and Singapore in December currently comes up as costing just over US$9,000 on the airline’s website. So first-class seats will be marketed to a select group of ultrawealthy flyers.

The four A350-900 planes will have a total of four first-class, 70 business-class and 58 premium-economy seats, while regular economy will not be available on these flights at all. The other A350 planes being retrofitted will have 42 business-class, 24 premium-economy and 192 economy seats.

The initial first-class-retrofitted planes will go into service in 2026.

Germany’s flagship carrier Lufthansa  (DLAKY)  is currently also reworking new first-class cabins, which set to debut on Nov. 9.

U.S.-based carriers like Delta Air Lines  (DAL)  have Delta One with lie-flat seats, and in some cases sliding doors, on long-haul flights. The exact design will vary with the routes and lengths of the flights.

“Over the past six years, we have extensively engaged customers and stakeholders in the design of our next-generation long-haul cabin products, anticipating their evolving preferences and expectations down to the finest detail,” Choon Phon said further.