However, domestic first class does have two very different meanings on certain transcontinental routes between New York City and California. Delta Air Lines, American Airlines, United Airlines, and JetBlue operate a special service on flights between John F. Kennedy International Airport and San Francisco International Airport or Los Angeles International Airport known as "Delta Transcontinental Service," "American flagship service", "United p.s." (p.s. stands for premium service), and "Mint," respectively, with Delta and United using specially configured Boeing 757-200s and American and JetBlue using Airbus A321s. In the cases of American and JetBlue, first class is actually a three-cabin first class which is different from two-cabin first class, both in comfort and price (such as lie flat seats in first class, for example).