The 126710BLNR is the GMT-Master II in Oystersteel with a Cerachrom bezel in blue and black. Rolex introduced that colour combination in 2013 on the 116710BLNR, the brand's first two-colour ceramic bezel, and continued it in 2019 on this reference with the new calibre 3285.
The most visible change in the transition was the bracelet: the 116710BLNR wore an Oyster bracelet, the 126710BLNR a Jubilee at its introduction. Since 2021 it has also been available on an Oyster bracelet. Calibre 3285 has about 70 hours of power reserve and an independently adjustable hour hand for those who travel between time zones. The case measures 40 mm and is water-resistant to 100 metres.
On a pre-owned example we look at the bezel, which does not fade but can crack from a hard knock, at play in the bracelet, which develops sooner on a Jubilee because of its many small links, at the clasp and at the completeness of the set. The 126710BLRO with a blue and red bezel is technically the same reference.