The product is a commemorative first day cover featuring a special stamp issued in 1984 to celebrate the centenary of the Greenwich Meridian. This historic line, which runs through the Royal Naval College in Greenwich, England, was chosen as the Prime Meridian by Greenwich Observatory in 1884. The cover would likely include a detailed description of the significance of the Greenwich Meridian and the celebrations held in 1984 to commemorate this important milestone in navigational history. It would be a collectible item for stamp enthusiasts and history buffs interested in British maritime heritage.