In the second half of the 20th century, 60 years, with the French company exchanges, experts in submarine operations, Rolex research model to meet the most stringent technical and professional requirements. Diving is not only the need to address water-resistance in extreme depth, its biggest problem is in the decompression, if look at the explosion, it has the potential to cause serious harm to other people inside the hyperbaric chamber. This issue is resolved valve placed in circumstances (in the 9 o’clock position), so to escape the pressure of helium chambers is gradually reduced to atmospheric pressure. Valve begins to operate the difference between external and internal watches more than 2.5 kilograms. Per square centimeter. The first patented helium valve at the end of September to the 1967 series of pilot Exchange 5513 delivered in 1969 and 1971. Small-diameter valve in these 5513s by the chrome-plated rather than stainless steel, so it is unusual to find them smoked oxidation.

In 1972, Rolex began producing helium valve special 5513s specifically for New York, the reference 5514. Dozens of examples of small hand-made in 1972 and between 1977. This time, small valves, and stainless steel. Circumstances behind engraved with serial number is usually delivered. Rolex 1520 caliber used in the two series.

Zoned under the full stop to the theme of Exchanges, which is worth bearing in mind that in the second half of 1960 and 1997, in addition to the two prototype Rolex Exchange provide other models, the use of acrylic crystal (5513 and 1665 standard) and Sapphire Crystal (from the last century since the 80′s).

In this case the same, red SUBMARINER, you should be careful, because some Exchange SUBMARINERS circulation and collectors resale market there are about 10-20 times greater than previous production Rolex.