A Zodiac and Seiko dive watch on Isofrane and Tropic Rubber Straps

Hands-On Isofrane & Tropic Rubber Watch Straps – The Italian Non-Silicon Vulcanized Compound Perfect for Dive Watches

The Skinny

  • Italian Rubber – proprietary non-silicon vulcanized compound
  • Isofrane sizes: 20mm, 22mm, 24mm – $139
  • Tropic sizes: 20mm, 22mm – $79

A Very Special Rubber from Italy

What everyone wants in a rubber strap may not be identical, but if you’re looking for the best dive watch straps, the Isofrane and Tropics are your best bet because the rubber compound and the smart heritage designs are unmatched.

Without getting into some misshapen chemistry lesson due to my lack scientific know-how, let me just conclude boldly as one who has handled hundreds of rubber watch straps that the rubber used on Tropic and Isofrane straps is simply the best there is. There’s no silicon, which means these straps don’t attract dust, hold yucky dead-skin bits, shine weirdly with sweat, cause allergic reactions, fade in the sun, or chaff the wrist. I’ve experienced all of these problems wearing nearly all other rubber straps.

An orange Tropic Vulcanized Rubber Strap's diamond pattern close up.
The distinctive outer surface of the Tropic Rubber strap.
An orange Isofrane Vulcanized Rubber Strap on a Seiko titanium Shogun dive watch.
Isofrane straps are made in Italy of a special Italian rubber.

Unless I’m seeking a special aesthetic, color, odd-ball size, filled end-lugs (which I don’t really like) or a specifically branded strap for a specific watch, I use either an Isofrane or a Tropic on nearly all my dive watches. My only complaint: I’d like 18mm Tropics and I’d like red versions of all these straps. Otherwise, I’m entirely sold.

Historically Significant, Presently Painless to Purchase

Both Tropic and Isofrane have a storied history as Swiss brands innovating in service of SCUBA during the 60s and 70s. Both brands developed forward-thinking rubber straps back in the day using a special form of neoprene. Today’s rubber formula has changed for the better in terms of both quality and environmental impact, but the basic design of both the Isofrane and Tropic remains unchanged. Those straps were pretty well sorted out back in the day, so they require no updates. Of course, this means the straps also look “era correct,” but they each look great on modern watches, too.

Isofrane and Tropic are not the only companies to use this special rubber compound, but they’re the only ones I know of that are neither more expensive watch-brand versions nor part of some vast watch strap catalog.

This is key. You go to Isofrane and buy Isofranes. You go to Tropic and buy Tropics. Easy, elegant, efficient – a boutique experience. I personally get overwhelmed by all the options out there today, and find that going for the best – here Isofrane and Tropic – trims back the time I waste hunting on my phone when I could be doing something more meaningful. I’m more than happy to pay the premium for that elegant purchasing experience.

Isofrane rubber strap pin buckle.
Isofrane’s hardware is signed beneath, so there’s no visible branding to clash with your watch.
Tropic Strap Rubber pin buckle.
Tropic branding is visible on the buckle, but doesn’t seem to clash with any watch, as it’s an iconic brand.
Orange Tropic rubber watch strap.

Isofrane for Big Dive Watches, Tropic for Smaller Ones

Both the Tropic and Isofrane straps are incredibly comfortable, durable, and secure, but very different. The Isofrane style is best on larger, thick divers, and the Tropic works better on smaller and thinner divers. You may disagree, but generally speaking this has been my experience. The Isofrane is pretty thick where it meets the lugs, and I’ve struggled to fit them on some watches. Conversely, the Tropic is thinner, and it becomes even thinner as it tapers away from the lugs, making it ideal on smaller dive watches. This is why I wish there were 18mm versions of the Tropic.

An orange Isofrane Vulcanized Rubber Strap on a Seiko titanium Shogun dive watch.
The Isofrane strap is thick, does not taper, and is suited to larger watches.
An orange Tropic Vulcanized Rubber Strap on a Zodiac dive watch.
The Tropic strap is thinner, tapers down to 16mm at the buckle, and is best suited to smaller watches.
An orange Tropic Vulcanized Rubber Strap on a Zodiac dive watch.
The Tropic strap tapers toward the ends, and becomes thinner as well. It is supple, and best on smaller dive watches.

Good People Doing Good Things

Today, both Tropic and Isofrane are part of the Synchron Uhren Manufaktur GmbH, which is an Austrian company which also owns the very cool Synchron watch company, Aquastar and Aquadive. Each of these revived brands has been the product of dive watch enthusiast Rick Maraei, who perhaps more famously revived Doxa back in the early 21st Century.

An orange Tropic Vulcanized Rubber Strap on a Zodiac dive watch.
The waffle pattern on the back of the Tropic strap along with the perforation keeps air moving acorss your skin. This 1960s design has yet to be improved upon.

I personally like that these companies all share a single-minded dive watch lover at the head, that they each focus on delivering very accurate and lovely recreations of vintage SCUBA watches and straps. The businesses are not why I buy Tropics and Isofranes, however. That’s down to the supple, durable, non-alergenic rubber compound, the exceptional and still relevant heritage designs, and the ease of just getting the best straps I know of and moving on to far more important endeavors, like SCUBA diving with cool watches.

Here’s a few more pics for you to peruse. Wear them in good health.

An orange Tropic Vulcanized Rubber Strap on a titanium Seiko Dive Watch.
Zodiac Super Seawolf on Orange Tropic Strap
Orange Isofrane watch strap