Many people are aware that the serial number of a Rolex watch may reveal the year of manufacture, but many are unaware that there is a similar indication on the band known as “clasp code.” This time, I’m going to take everyone to hear about the “clasp code.”
What is the clasp code?
In addition to the production serial number etched on the watch head of Rolex watches, another code of numbers will be engraved on the strap based on the year of manufacture. Unlike the serial number on the header, the clasp code of the strap is not as accurately recognized and matched. It can also be used as a guideline, despite the fact that it is incompatible with the year stated on the header. The strap’s clasp code may be located on the buckle’s “right of the logo.”English words and digits “F3” are carved above the “STTELINOX” stamp. This is known as the “clasp code.” STTELINOX’s “INOX” is Inoxydable from French, which means “not oxidized,” which signifies stainless steel. Most common watches are stamped “stainless steel,” but Rolex opted to mark with STTELINOX, which is unusual.
The timepiece used in the picture

This watch’s serial number is ‘A prefix,’ and it was manufactured in 1999. The serial number on the strap is likewise ‘A prefix,’ and it was manufactured in 1999. The two serial numbers have the same year.
The strap replaced, the label will change as well
It should be noted, however, that if the strap is replaced, the serial number will differ from the original strap. If it is changed in an authentic Rolex factory, a “S” will be put to the serial number of the strap to indicate that it has been replaced, thus if you see the mark of S, you know that the year represented by the watch head and the serial number on the strap will be inconsistent.Of course, the strap could not have been changed at the original manufacturer, but even though there is no ‘S’ indication, the possibility that the strap has been replaced might be considered. Furthermore, whether it is the watch band serial number or the manufacture serial number, these decisions do not technically constitute public Rolex records and may only be used as guidelines.
Before 1976, the strap serial number only had numbers
Because the inclusion of English characters to the serial number did not commence until 1976, Rolex watches manufactured before to 1976 would not have English letters in the serial number of the watch band. The year can also be determined if the serial number contains only “numbers” and no English letters. Before 1976, the serial number of the watch band is distinguished by an extra number etched above the 2-digit number. It is extremely simple to determine the manufacture year. The serial number represents the final two digits of the year. To begin, the watch band’s serial number is “66,” indicating that this watch was made in 1966.
The timepiece used in the picture

ROLEX Oyster Perpetual Date Ref.1501
The outer ring of this vintage watch is shaped like an airplane’s engine-turned bezel, which is unforgettable. In the early days, the crown symbol on the huge 6 mm crown and the rivet bracelet extending on both sides of the strap were both unique designs.
The older the strap, the more valuable it is
If your Rolex still has its original strap, it is quite desirable. When you see that the serial number on the bracelet only has numbers, you may presume that this is an antique watch. However, because to the wear and tear of the strap, most watches also replace the original strap, therefore it is extremely uncommon for the head of the watch and the brace to have the same serial number and year. The brace and its serial numbers and the header can vary by many years for earlier watches, though. This needs to be known too.