The models 756 and 756 UTC, however, are much more than the chronograph variants of the pilot's watch 656. New materials and new technologies raise these models to a level of robustness and insensitivity to external influences that go far beyond any conventional measure.
This starts with the type of stainless steel that is used for the case of these watches. The used alloy is nickel-free. In addition, this stainless steel is ice-hardened and thus achieves a hardness of 60 HRC (Rockwell) or 710 HV. This corresponds to a three- to four-fold hardness compared to normal stainless steel with nickel.
Also completely new is the patented crown and pusher system of the 756. The two consecutively arranged seals, made of a material used in vacuum technology and chemistry, prevent the ingress of moisture into the watch case. These seals are highly resistant to almost all known chemicals and additionally protected by a permanent lubrication. The same task comes to the glass seals, which are also made of a new material and, in addition to excellent chemical resistance, are especially resistant to UV rays.
The moisture which can still penetrate in the watch case, can be entrusted to the Dehumidifying Technology by Sinn. The model 756 this is a drying capsule filled with copper sulfate, which receives a possibly post-defunded humidity. Result: longer functional safety of the movement. Practical advantadge: The cover glass does not start, the readability is guaranteed.
All bearings are oiled with Sinn Special Oil 66-228. This allows the rate of watch to be guaranteed for the exceptional temperature range of -45° to + 80°C.
Understated black on black, the models of line 756 show at the 9 the stylized magnetic field lines around a magnetic core. They symbolize a magnetic field protection up to 80,000 A/m or 100 mT (milli-Tesla) or 1,000 gauss.
The engine of the 756 chronographs is the highly accurate and proven Swiss movement Valjoux 7750. On the high-contrast dial time, stop second, stop minute and stop hour can be read excellently. Under a sapphire crystal glass, which grants a clear view even in low light conditions by its antireflective coating on both sides.
The model Sinn 756 UTC adds a dual timezone to these features. It is displayed by yellow framed hands from the center of the display.