Ollech & Wajs Swiss Automatic P-104 Selectron Pilot's Watch #OW-P-104-Selectron

You may never have used a slide rule. Since the advent of the electronic calculator, few people have. However, before the 70s, slide rules were used for everyday arithmetic, such as calculating ratios, percentages, unit conversions, multiplication, and division. From the mid-century, wristwatches with miniature slide rule scales were used by scientists, engineers, and pilots to calculate things like fuel consumption, airspeed, ground speed, and the rate of climb or descent. Throughout the 60s Slide rule watches were ubiquitous amongst workforces in the burgeoning field of ‘aerospace engineering’, from NASA to General Electric. Ollech & Wajs ‘Selectron Computers’ were amongst the most popular slide rule watches of this period. Back then, the word ‘computer’ described a person who carried out calculations or computations, rather than a programmable machine capable of processing digital data.

The OW P-104 Selectron shares many of the basic characteristics of its historic forebears. It has a bi-directional bezel with logarithmic scales that can perform a multitude of calculations with a single rotation. It’s faster than a so called smartwatch, doesn’t require a battery and can be used underwater, up to 300m if necessary (that really is smart!)

The high contrast dial, which evokes the stark simplicity of cockpit instrumentation, features ivory indices and a vivid orange Super-LumiNova® handset, for maximum visibility in low light. The regimental-style RAF strap is another nod to Selectron’s historical links to military aviation.

Inside the OW P-104 Selectron is OW’s own inimitable bespoke Soprod Newton Precision P092. This outstanding automatic calibre is independently tested for dependability and durability at the internationally renown Laboratoire Dubois in Chaux-de-Fonds. It is modified to OW’s specifications and adjusted in five positions, the movement has been finished in accordance with our rugged aesthetics, and ‘OW Zurich 1956’ is engraved into the nickel-plated base, on which sits a co-designed, custom rotor in the shape of the OW marque.


The OW P-104 Selectron is presented on a regimental-style nylon RAF strap.