Tetra

The NOMOS Tetra 408 is the larger closed-back version of the original Tetra design, with a 29.5mm square stainless steel case, white silver-plated dial, tempered blue hands, and manual winding. Like the earlier Tetra references, it has gone through several hand-wound movement iterations over time, including 1T, 1TS, and 1TSP executions before the current Alpha calibre. The case measures 29.5mm by 29.5mm, with a height of 6.5mm and a lug-to-lug length of 40.5mm. It has a sapphire crystal front and a stainless steel back fixed with four screws. The Tetra case is defined by its square shape, stepped lugs, compact proportions, and flat profile. Current specifications list water resistance at 5 atm, an increase from the earlier 3 atm rating. The galvanized white silver-plated dial uses the Tetra’s square minute track, printed Arabic numerals, and a recessed small seconds display at 6 o’clock. The tempered blue steel hands provide contrast against the pale dial surface. The display consists of central hours and minutes with subsidiary seconds. Power currently comes from the NOMOS Alpha, a manually wound in-house calibre measuring 10 ½ lignes in diameter and 2.6mm in height. It has 17 jewels and a power reserve of up to 43 hours. The movement history of this reference reflects the broader development of NOMOS’ early hand-wound calibre family. The watch is supplied on a black Horween Genuine Shell Cordovan strap with an 18mm lug width.