Rolex Milsub 5513 made for the British Royal Navy, '70s

Stainless steel round case, n.3927201, fixed spring bars, black aluminium bezel turned to blue, case-back engraved with the Broad Arrow and issued "0552/923-7697, 370/75", serial number repeated inside.Black dial, luminescent indexes, encircled “T”, sword-shaped hands.Automatic movement, cal. 1520.Fabric NATO strap.Size: 40 mm.Accompanied by Rolex service receipt.Notes: In the 70s the British Ministry of Defense commissioned Rolex for a watch with strict military specifications: fixed spring bars welded to the lugs for greater robustness, a 60-minute calibrated bezel insert, large sword-shaped hands for enhanced readability, and a luminous dial marked with an encircled “T” indicating the use of tritium.Rolex modified its Submariner reference 5513 with the above requirements, and the “MilSub” was born.When decommissioned these watches -according to research about 1200 units- were sold by the MOD during the 80s, and purchased by civilians and dealers who often replaced the military-specific components to transform them into standard Submariners. Thus, very few MilSubs have survived with their military configuration.The present specimen features all the correct Milsub characteristics and excellent conditions, and it is correctly marked with the "0552" code for British Royal Navy, the "923-7697" code for NATO, followed by the issue number "370" and year of issue, "75".