The airline's international services with existing cabins feature the fully reclining First Class Skysleeper Solo or Skysleeper; Executive Class Seasons Shell Flat Seat or Skyluxe Seat; Premium Economy Sky Shell Seat; and Economy Class.[161] The First Class Skysleeper Solo reclines fully and features genuine leather upholstery from Poltrona Frau of Italy.[162] The Executive Class Seasons Shell Flat Seat is a lie-flat design with the ability to lower armrests to the same height as the seat when reclined.[163] Premium Economy is a recent addition, it was first introduced on the Tokyo–London route on 1 December 2007.[164] It features a shell-shaped seat that allows passengers to recline by sliding their seat forward, without having the seat in front intrude when reclining.[1