Designing the Coefficient

An in-depth discussion about PAR WEBER's design philosophy and how we applied this approach to developing the Coefficient, the first timepiece to feature our always-on Enduro-Lume™ illumination system.


Whether it be the sweeping eagle in his flight, or the open apple-blossom, the toiling work-horse, the blithe swan, the branching oak, the winding stream at its base, the drifting clouds, over all the coursing sun, form ever follows function, and this is the law.


PAR WEBER's approach to design differs from our watchmaking peers.

Most watchmakers start the process with an aesthetic inspiration - a wristwatch they admired, or a style they believe to be underserved in the market. As a result, consumers today are spoiled for choice. You can purchase anything from watches with unconventional one-hand displays to vintage-inspired timepieces that often surpass the refinement of the originals they were based upon.

At PAR WEBER, our mission is to design and deliver superior equipment. In contrast to an aesthetics-first approach, our design process begins with a set of performance and functional objectives, and we consider aesthetics in service of those objectives. The Coefficient's industrial appearance is the result of this philosophy.

Of course, we would argue that the Coefficient does, in fact, have a certain aesthetic appeal - the kind found in other performance-built equipment (photography gear, mountaineering hardware, military kit, and so on). But our tastes admittedly favor idea that the beautiful object is one that performs its job well.



We set forth three major performance objectives for the Coefficient:

  1. Legibility and fast 'speed to read' in light and dark conditions (legibility)
  2. Ruggedness and durability (toughness)
  3. Excellent timekeeping accuracy with low maintenance requirements (reliability)


This objective was highest priority and what led to development of our always-on Enduro-Lume™ system. We won't go into detail on Enduro-Lume™ in this piece (click here to learn more), but it is a patent-pending illumination system that is always on, is not radioactive, and has a service life as long as the timepiece.

There are three elements that drive legibility and fast "speed to read" in ambient light conditions:

The Coefficient's face is optimized for at-a-glance legibility in ambient light or when illuminated by Enduro-Lume™.

  • A high contrast between hands and dial
  • An uncluttered dial with few intersecting lines
  • Distinctive hour and minute hands that minimize the chance of confusing the two


These factors led to our black-hands-on-white-dial face design, the limited use of extraneous markings on the dial, and shape-specific hour and minute hands. Because Enduro-Lume™ illuminates the entirety of the watch face from the bezel inwards, factors that enhance daylight legibility tend to do the same for legibility under illumination.



Damage resistance has been an important design factor for watches since they migrated out of pockets and onto wrists during World War I.

But defining ruggedness and durability can be subjective. Some watches pride themselves on their massive size and weight. Dive watches are now routinely marketed as water resistant to 1000M - a claim we hope that no one endeavors to test firsthand.

Our objective was to harden the watch against its most common foes: concrete and asphalt, rocks and dirt, door handles and dishwater. The watch should be safe to wear in the surf of the summer and over a jacket sleeve when it's cold (as some of us do here in the extended Chicago winter).

The Coefficient achieves this through materials choices that are time-tested: a machined stainless steel construction for strength, PVD coating for abrasion and impact protection, a sapphire glass crystal for scratch resistance, and substantial guards around the crown.

The Coefficient is also engineered to a water resistance depth rating of 100M / 330ft, which we consider to be the minimum rating for worry-free water sports.



For "set and forget" accuracy, superb reliability, and maintenance-free operation, the quartz movement is unsurpassed. The Swiss-made Ronda 715 that powers the Coefficient is a repairable, gold-plated, 5-jewel movement. It is so accurate that you will likely need to change the time for daylight savings before you observe a deviation beyond a matter of seconds.

Quartz movements are also remarkably robust and long-lived; failures are rare and tend to be associated not with the movement itself but with water damage or other unrelated defect (e.g., a loose hand that falls off its pinion). Many of us who wear mechanical timepieces are accustomed to paying $400-500 every four years to have them serviced. This is not necessary with the Coefficient.

A quartz movement also makes a logical pairing to our Enduro-Lume™ illumination system, which derives power from its own coin cell battery. Because the battery change intervals are calibrated to be synchronized between the quartz movement and the Enduro-Lume™ system, the watch does not need to be opened more frequently than any other quartz-powered timepiece.



In parallel, we articulated what features on a wristwatch are the most indispensable:

  • A date function
  • A timing bezel
  • Thoughtful ergonomics
  • Useful information on the case back



Beyond knowing the hour, minute, and second, having the date on your wrist is the next most useful marker of time. The choice of a traditional 3 o'clock date window also helps to rapidly orient the user to the watch face when reading the time.



Like precision timekeeping itself, the impetus for the timing bezel was originally navigation. Its earliest incarnation was the Weems second-setting watch. This watch had an interior seconds-tracking disc that helped aviators synchronize their seconds hand with a radio signal in order to accurately calculate longitude during transoceanic flights.

The modern external rotating bezel was popularized with dive watches of the 1950s and today its usefulness is demonstrated in many contexts. Not only is it handy for tracking elapsed minutes, but it can mark the offset for a second time zone and even assist in compass navigation. When we canvassed watch-wearers about how they used their timing bezels, we also were interested to learn about its fairly common use as a scorekeeper and counter.

The Coefficient's sparse markings at each quarter turn of the bezel are deliberate - the red '0' marker makes identifying the orientation of the bezel instantaneous and aligning the bezel figures with the markers on the chapter ring enables to-the-minute timing.



Nearly every decision related to case and component design required careful consideration of how it will impact how the watch 'wears' and how it operates. We put particular emphasis on the three elements that directly impact the daily experience of wearing the Coefficient: the bezel, the crown, and the lugs.

"Aperture ring" bezel

With its a tall, tooth-edge grip, the Coefficient's "aperture ring" bezel (so-called because of its resemblance to the clicking aperture ring on camera lenses) provides plenty of purchase for fingers, regardless of whether you are barehanded or wearing gloves. Its prominence on the watch itself means it is easily found by touch alone, and the fact that it is bidirectional means that you don't need to go all the way around if you miss a setting by a single click. It is a pleasure to operate.

The tall profile of the "aperture ring" bezel makes it a pleasure to use.

The Coefficient's high-mounted, extended crown has offset crown guards, making it easy operate without removing the watch from your wrist.

Extended crown

The Coefficient's crown is similarly designed for easy operation. Extended outside the bezel, it is easily operated with the pads of the fingers (in contrast to other wristwatches our team members have owned, which have small crowns that require clawing at with fingernails). Because it is mounted high on the case, it is more comfortable to wear and is easier to operate without removing the watch from your wrist. The crown guards are offset to the lower half of the crown itself, which provides protection while preserving easy access.

Low-slung, 20mm-wide drilled lugs

The Coefficient's lugs are mounted low on the case and conform to the shape of the wrist. This enables the Coefficient to comfortably accommodate a huge range of wrist sizes. The lugs' 20mm width is a standard size which gives ample choice to swap out third party straps, and their drilled-through lug holes make removal of spring bars a simple matter.



In addition to the conventional markings you typically find (such as the Coefficient's Swiss movement origin and 100M water resistance rating), we have inscribed useful reference information on the case back. The kinds of things that are handy to know in case you forget them or would like to know them without opening the watch: the movement model (Ronda 715), which batteries are required for the movement and Enduro-Lume system (371 and CR2025, respectively), and the lug width for purchasing replacement straps.



A common pitfall in product design is losing sight of the original purpose. Strong concepts can end up confused by a desire to be everything to everyone, diluted by committee-based decision making, or derivative out of fear of the new. Designing the Coefficient was no exception - one of the major challenges we encountered was resisting the temptation to add extraneous features, adornment, or new requirements.

We are very proud that the final product is true to the original objectives set forth, and we believe you'll find that there are few timepieces that can match the Coefficient's performance across these criteria.

Click here to see the Coefficient, and here to learn more about Enduro-Lume™.



Copyright 2019 PAR WEBER