The Sinn 556 is one of the most popular flieger style watches. While there are various configurations available with different dial styles, strap types and seconds hand colors, there are two main differences are between the 556.A and 556.I and it all comes down to the dial design.
The main differences:
The 556A has large Arabic numbers 3,6,9,12 and a smaller date window at 4:30. The only text on the dial is Sinn and Made in Germany.
The 556I has all stick markers with a date at 3:00. The date window is larger. There is text at 6:00: “Automatik”, the German spelling of automatic.
Sinn 556 RS:
There are also RS versions of the 556A and 556I models. The “RS” gives the watch a red seconds hand.
Date Font Weight:
Despite the stock images above making it appear that the date on the A is bolder than the I, this is not necessarily the case IRL. In real life examples, the date on the A has been found to have a font weight similar to the I. This is not to say there are no 556 A models with bold font. Please share your experience below…
Other than the differences mentioned above, the different versions of the 556 share the same specs, including size, materials and movement.
Sinn officially writes the model numbers as 556 A RS with spaces. You may also see the numbers expressed as 556.A or 556A. The title of this post was written 556A for SEO purposes.