The Frankfurt watch manufacturer Sinn offers this model as an entry-level watch since December, 2007. It impresses with its clear appearance and the easy-to-read dial. For an affordable price, it is a high quality and reliable watch. It is equipped with a sapphire crystal glass with anti-glare treatment on both sides. The movement is the simple and robust ETA 2824-2, visible through a display caseback with sapphire crystal.
The model 556 has an almost-identical case and dial to the then-current Sinn 656, though the 556 features slightly different finishing and the display caseback, which adds 1 mm in thickness. Both watches use the popular ETA 2824-2 movement. The model 656 was retired from the catalog in 2012, leaving the 556 and new Sinn 856 to take its place.
The watch uses a satin stainless steel case without the company's proprietary hardening or anti-moisture technologies. It does have a screw-down crown for pressure resistance to 20 bar, and meets DIN 8310 requirements for waterproofing.
The original model 556 featured simple bar markers and a traditional date window at 3:00. This would be renamed model 556 I in 2011 when the 556 A with numerals at 3, 6, 9, and 12 was added. The 556 I was also offered with a mother of pearl (light or dark), blue, and brown dial, all with no date window.
In 2013, Sinn collaborated with the Stiftung Waisenhaus youth home and "Frankfurt am Main" naval ship to produce a commemorative model with the silhouette and ID number of the ship on the dial. The special 556 Anniversary model in 2016, a limited edition of 1,000 pieces celebrating 55 years for the brand, featured an anthracite dial and no date window.
- 556 (2008-2010) - Bar markers, black dial, date window at 3:00
- 556 A (2011-present) - Arabic numerals at 3, 6, 9, 12, date window at 4:30
- 556 Anniversary (2016-2018) - Bar markers, anthracite dial, no date, limited to 1,000 pieces
- 556 I (2011-present) - Bar markers, black dial, date window at 3:00
- 556 I B (2018-present) - Bar markers, blue dial, no date
- 556 I EGV Frankfurt am Main (2013) - 556 I with "Frankfurt am Main" naval ship silhouette and ID number A 14112 on the dial, not a limited edition
- 556 I M (2016-present) - Bar markers, brown dial, no date
- 556 I Mother-of-pearl S (2018-present) - 556 I with dark mother of pearl dial, no date
- 556 I Mother-of-pearl W (2016-present) - 556 I with light mother of pearl dial, no date