Jaeger-lecoultre, Master Series, Model: 1378420, with a diameter of 39mm, features a silver-white radiating dial and classic Toffee hands. It integrates date display, power reserve display, and a small seconds sub-dial in an inverted triangular layout. It is equipped with a self-produced K gold automatic rotor with a transparent back. The case is thin and light with smooth and round lines. The folding clasp makes it comfortable to wear. It is a highly popular model in the Master series and is affectionately called "The Joker" by watch enthusiasts. The complete set at the end of 2021 is in very new condition.