Tetra Basalt / Closed Case Back

Reference 440.SB is the closed-back version of the NOMOS Tetra Basalt, part of the Tetra Origins series. It combines the square 29.5mm stainless steel Tetra case with an anthracite dial, rhodium-plated hands, a yellow seconds hand, and the hand-wound DUW 4001 calibre. Within the four Tetra Origins executions, Basalt is the darkest version, alongside Ochra, Terra, and Salvia. The stainless steel case measures 29.5mm by 29.5mm, with a height of 6.5mm and a lug-to-lug length of 40.5mm. It is fixed with four screws and fitted with a sapphire crystal front and a closed stainless steel back. The Tetra’s double lugs remain one of the defining external elements of the design. Water resistance is rated to 5 atm. The anthracite dial uses the Tetra’s mixed numeral and marker layout, with a square minute track and a small seconds display at 6 o’clock. The sub-dial combines anthracite, fuchsia, and yellow accents, while the yellow seconds hand adds a contrasting colour element within the darker dial composition. Rhodium-plated hour and minute hands contrast with the dial surface. Power comes from the NOMOS DUW 4001, a manually wound in-house calibre measuring 10 ½ lignes in diameter and 2.6mm in height. It has 17 jewels, a power reserve of up to 53 hours, and uses the NOMOS swing system. The watch is supplied on a beige vegan velour remborde strap with an 18mm lug width.