While at first glance the Tetra may seem like 'simply' a square version of the Tangente, there are actually a few other changes that give this watch its own personality. Did you ever notice the change in the numerals, or the Art Deco'esque stepped lugs?
Reference 401 has a case of 27.5*27.5mm and a stainless steel back. It is powered by the hand-wound Alpha caliber.
The Alpha caliber is NOMOS Glashütte’s highly acclaimed classic. It was our first movement—and the one that still powers more of their watches than any other. Robust, accurate and reliable, it ticks inside Tangente, Ludwig, Tetra, Orion and Club and all the watches in the 33 Series.
Decentralized seconds, stop-seconds mechanism, Glashütte three-quarter plate, 17 ruby bearings, Glashütte stopwork, Incabloc shock protection, balance spring from Nivarox 1A, adjusted in six positions, tempered blue screws, rhodium-plated movement surfaces with Glashütte ribbing and NOMOS perlage, ratchet and crown wheel with Glashütte sunburst