On Delta Air Lines, S class is a specific revenue fare bucket primarily used for Delta Comfort+ seats. Introduced as part of a fare realignment to offer more transparency, S class serves as a mid-tier entry point for the Comfort+ cabin, often sitting just below the "W" class in terms of price. When you book a ticket in S class, you receive the standard Comfort+ benefits, which include up to 3 inches of extra legroom, dedicated overhead bin space, and early boarding (usually Zone 3). This fare class is used for both domestic and international markets and is also the inventory code often utilized for complimentary Medallion upgrades into the Comfort+ section. Because it is part of a "dual-inventory" check system, the availability of an S class fare depends on both the Comfort+ cabin capacity and the availability of the underlying Main Cabin fare.