The Sinn 556 I, product number 556.010, is a three-hand automatic watch from the Frankfurt maker, with a sparse dial design that draws on the brand’s pilot and navigation cockpit clocks. The satinized stainless steel case measures 38.5 mm in diameter and 11 mm thick, with a 20 mm lug width and a weight of 65 g without strap. The glossy black dial uses indices and hour and minute hands coated with luminescent colour. A sapphire crystal, anti-reflective on both sides, protects the dial, while a screw-fastened sapphire case back shows the Sellita SW200-2 self-winding movement, which runs on 26 jewels at 28,800 semi-oscillations per hour. The watch is water- and pressure-resistant to 20 bar.

Functions comprise hours, minutes, seconds and a date display, and the movement includes a seconds-stop function for precise time setting. Sinn states that the movement is anti-magnetic in accordance with DIN 8309, while the case, with its screw-down crown, meets the water-resistance requirements of DIN 8310 and is also rated as resistant to low pressure. In the configuration described here, the 556 I is supplied on a satinized solid stainless steel bracelet, which Sinn prices at €1,640; the same watch can be configured on other straps from €1,290. The conventional 20 mm lug width makes it easy to fit aftermarket straps, and Sinn provides a two-year warranty on the watch.

The 556 I has a strong reputation as a straightforward everyday tool watch. Teddy Baldassarre praised its legibility, 38.5 mm sizing, satin-finished case and value for money, and preferred it on the bracelet, while WatchGecko singled out its build quality and legibility, describing the fit and finish as exemplary for the price. The most frequent criticism concerns the bracelet clasp, which reviewers and owners describe as simple, chunky or prone to scratching; Teddy Baldassarre also noted that the screw-down crown and its guards are somewhat pronounced. Some owners mention modest lume and power reserve. The 556 I (556.010) is currently in production and is offered for sale on Sinn‘s official website.