Casio’s Most Purpose-Built Tool Watch Ever Finally Arrives in the US

Casio’s affordable SAN-100H watch was built to withstand environments not even the most burly G-Shock model dares to go.

Black Casio stopwatch with white and orange hands and a coiled black cord attached.

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By Jack Seemer

Published March 9, 2026

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No doubt about it: G-Shock makes some of the toughest watches on the planet. They can survive hard drops, deep-sea diving, hell, even combat zones across some of the most demanding terrain known to man.

But there is still one place you might not want to take even the most burly G-Shock: the spa, where steam and rapid fluctuations in temperature can wreak havoc on a watch’s various components.

Coincidentally, it’s exactly the environment that inspired a purpose-built timepiece from the brand’s parent company.

Black Casio stopwatch with white dial, orange second hand, and white strap on a wrist. — The SAN-100H isn’t just suitable for the sauna or steam room. Casio made it specifically for them.

Turn up the heat

Limited to Japan since inception, the Casio SAN-100H is finally available in the US for the first time in two years.

What’s more, it costs just $110, making it not only Casio’s most purpose-built tool watch but one of the cheapest, too.

Wristwatch with a white dial, black bezel, and orange and white strap worn on a wrist holding a wooden object. — The Casio SAN-100H is a purpose-built tool watch if there ever was one.

It’s not that the SAN-100H is simply suitable for saunas and steam rooms. Casio made it for them, and the watch packs a handful of novel features that make one of the most resilient watches in its catalog.

Back of a Casio SAN-100H watch with black case, white and orange strap, and water resistance details. — The resin case minimizes contact between metal and skin. The screws, for example, are recessed.

For starters, the SAN-100H features a special battery rated to 212 degrees Fahrenheit (the boiling point of water). The case also uses a low-moisture-permeability resin.

Meanwhile, recessed screws minimize metal-on-skin contact — one of obvious reasons to avoid other watches in the sauna, irrespective of what such places can do to the internals.

Finally, a traditional band makes way for a spiral cord strap, fashioned after traditional locker keys. Like the case, it’s devoid of metal, meaning it won’t conduct heat like a bracelet would.

Black Casio wristwatch with white dial and orange translucent strap worn on a wrist. — The spiral band is fashioned after traditional locker keys.

As far as the actual functionality goes, the quartz-powered SAN-100H is rather simple. It features just two buttons, which cycle through a regular analog display and 12-minute timer.

Black Casio wristwatch with round face, white numerals, and orange minute hand on a wooden surface. — Beyond telling time, the watch features a 12-minute timer.

It’s worth clarifying that Casio advises against wearing the watch in the sauna for more than 15 minutes at a time. And water resistance taps out at kist 50 meters (most G-Shocks are four times that amount).

Availability and pricing

The Casio SAN-100H comes in two colors: black and white with orange accents. It costs $110 in the US.

Black Casio wristwatch with round face, white numerals, orange second hand, and coiled plastic band.

Casio SAN-100H

$110 at Casio

About the Author:

Jack Seemer is the executive editor at Gear Patrol, with over a decade of experience in product journalism. He currently reports on a wide range of topics, including footwear, watches, EDC, cookware and more.

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