The bracelet links are also much thicker than on the 5402, however it somehow feels lighter in hand.
The case is equipped with a sapphire case-back, allowing for a clear view of the Manufacture Movement Cal. 2121 - the exact same movement used in the 5402. This makes the case and bezel slightly thicker.
The arch of the bracelet joining the case makes the watch sit a little awkwardly on smaller wrists, but if your wrist is flatter than it is round, the watch sits very nicely on the wrist. When sized correctly the watch slips away unnoticed thanks to the delightful ultra thin case.
The watch is equipped with a double deployant clasp - which has to be closed following a certain order. Very accustomed to vintage pieces with single folding clasps, this took me a little getting used to.
The manufacture caliber 2121 is the exact same movement used in the original ref. 5402. The movement was originally sourced from Jaeger LeCoultre, also used by Patek Philippe in the Nautilus 3700. The rights to the 2121 were subsequently bought up by Audemars Piguet, who has since reworked and redecorated it into what keeps the 15202 ticking today.