Casio’s Glow-in-the-Dark Pro Treks Become Its First Digital Watch With a Fully-Lumed Dial

Casio has been pushing the boundaries of outdoor watch tech for three decades now, and just when you think they’ve exhausted every possible innovation, they manage to drop something completely new and unexpected. 

The Japanese watchmaker has just dropped two new models in their adventure-friendly Pro Trek line, the PRW-35LD-5JF and PRW-35TLD-7JF, which introduces its first-ever phosphorescent digital LCD display that literally glows in the dark without using the backlight.

Not Just Cashing in on a Trend

Chargeable lume is nothing new in the watch world, with the ubiquitous Super-LumiNova and Seiko’s LumiBrite both emerging in the ‘90s as safer non-radioactive alternatives to tritium tubes. But while these types of coating have been gracing indices and handsets for over 30 years now, the recent trend of fully-lumed dials is increasing in popularity. Brands like IWC, Ressence, and Zodiac have all cashed in, but this type of glow-in-the-dark coating is much easier to achieve behind an analog ticker. As for the digital watch world, leave it to Casio to be the innovators. 

One of the brand synonymous with digital watchmaking, Casio has been a major player since the launch of their Casiotron in 1974, the first digital timepiece with an electronic calendar function. As for the Pro Trek line, it’s become a mainstay for hikers and adventurers since debuting in 1995, with its 1999  PRT-1GPJ (aka “Satellite Navi”) becoming the first wristwatch with a GPS sensor.

Needless to say, a fully-lumed dial isn’t quite as groundbreaking, it’s pretty darn useful in the field. While Casio’s Super Illuminator LED and its Afterglow backlight help light up the dial with the push of a button, they also turn back off after a couple of seconds. As for the green-glowing phosphorescent lume, it serves as supplementary to the LED, lighting the dial automatically throughout the night, as long as it’s been charged by the sun throughout the day. This is crucial for, say, climbers or mountain bikers going out at night who don’t want to use a second hand just to check the time.

Glowing Innovation

First introduced in Casio’s PRW-61LD (LD for “Lume Dial”) back in 2023, Neo-Brite is the name given to the proprietary lume. However, with those ana-dig watches, the green glow was simply given to the analog portion of the dial — not the digital LCD screen at the bottom. Casio claims that shining a 200-lumen headlamp on the watch for just one minute will result in visibility for about an hour afterwards, so you wouldn’t have to worry about this thing going out on you.

For this upcoming all-digital release, these new PRW-35 variants take things a significant step further by implementing the technology directly into the digital LCD screen itself for the first time. Considering the sparse information given on the timepieces, it has yet to be made clear if the lume is, in fact, the same Neo-Brite used for the analog dials. But if so, it will be a game-changer for the brand.

Premium vs. Practical

The two new models showcase Casio’s typical high-low approach to their outdoor line. The PRW-35LD-5JF at just above $300 represents the more accessible entry point with a bio-based resin band, gray IP bezel over a black case, and standard mineral glass. Meanwhile, the PRW-35TLD-7JF, for around double the price, elevates the experience with premium materials including sapphire crystal with internal anti-reflective coating, a titanium band, and titanium carbide treatment on both the bezel and bracelet for enhanced scratch resistance and color depth. Both models feature biomass resin cases with stainless steel rotating compass bezels.

The two watches also maintain the same relatively compact dimensions that have made the PRW-35 line popular among hikers who don’t want a bulky monster strapped to their wrist, coming in at 44.6mm across, 51.2mm lug-to-lug, and 13mm thick. The titanium-banded model unsurprisingly adds some weight at 81g (~2.86oz) compared to the resin band’s mere 45g (~1.59oz), but that’s still remarkably light considering the features you get.

Outdoor Essentials Intact

While the luminous LCD is the headline feature, these watches don’t skimp on the typical Pro Trek functionality. Both models pack Casio’s reliable Triple Sensor technology for measuring altitude (with 1-meter precision), barometric pressure (with trend graphs and alarms for sudden changes), compass bearings, and temperature. The usual Tough Solar movement is always a fan favorite, while Multi-Band 6 radio-controlled time adjustment keeps your watch accurate and can give you sunrise/sunset times.

Water resistance is rated at 100m, making these suitable for most water activities short of serious diving. The -10°C (14ºF) temperature resistance means they’ll keep ticking even when you venture well below freezing, which is crucial for high-altitude expeditions.

Spec Sheet

Pricing & Availability

Both models will be released overseas this May, with the PRW-35LD-5JF priced at ¥48,400 (~$337) and the premium PRW-35TLD-7JF at ¥88,000 (~$613). Unfortunately, international availability remains uncertain since Casio has historically been selective about which Pro Trek models make it to the U.S. market and previous PRW-35 models have had limited release outside Japan. Given the innovative display technology, however, these might have a better chance of global distribution than their predecessors.

Recap

Casio Pro Trek PRW-35LD-5JF & PRW-35TLD-7JF

Casio takes its fully-lumed Neo-Brite dial used for analog dials and puts it on a digital display for the first time with these upcoming Pro Trek watches.

Learn More: Casio