The circa 1991 x-serial 16570. Explorer II features a black dial and a fixed numbered GMT bezel. The case and stainless steel Oyster bracelet remain in good condition. The bracelet has very little stretch. As configured the watch will accommodate a 7 ½ inch wrist. Powering the 16570 is an automatic Rolex caliber 3185 with an approximate power reserve of 50-hours.