The ISOfrane® strap is the ventilated rubber dive strap that helped define what a dive strap should be. Born in the 1960s and crafted from natural rubber, it gave divers a supple, breathable alternative to the heavy steel bracelets of the day. Production later stopped, and in 2010 Synchron revived it. Today it is made in Italy and remains one of the most recognisable straps in diving.
A legend from the golden age of diving
The original ISOfrane® strap was developed during the golden era of scuba exploration. Steel bracelets were durable but cumbersome under the pressure and movement of a deep dive. ISOfrane® answered with a strap that was highly flexible, resistant to saltwater and UV, and vented to reduce sweat. It was not only functional but iconic, and dive-watch makers including Aquastar, Doxa, and Omega paired it with their flagship models, cementing its status among professional divers.
The ladder-slot design
The ISOfrane® signature is its ladder of vertical ventilation slots running the length of the strap. They increase airflow and let water and sweat escape, so the strap stays comfortable on a hot deck or a long dive. A ribbed underside adds grip and comfort against the wrist, and the natural-rubber construction keeps the strap flexible enough to move with you rather than against you.
The rubber, and what is not in it
The genuine ISOfrane® is made in Italy from vulcanised natural rubber. Vulcanisation gives it strength and elasticity that last. Just as important is what it leaves out: no silicone, no FKM, and no PFA. That means none of the plasticky feel or dust-magnet behaviour of silicone straps, and a material chosen purely for performance and comfort.
Revived by Synchron, true to the original
When ISOfrane® production ceased, the strap became a sought-after piece of dive-watch history. Synchron revived it in 2010, staying faithful to the original design ethos while building it with a modern vulcanised compound. The result is a strap that looks and wears like the 1960s legend, made to last today.
Sizes and buckles
The ISOfrane® strap is offered in 20mm, 22mm, and 24mm lug widths, and in a choice of buckles: the forged RS, the stamped IN, and a DLC-coated version. Each has its own character, covered in the ISOfrane® buckle guide.
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Frequently asked questions
What is an ISOfrane® strap?
It is a ventilated natural-rubber dive strap, originally from the 1960s, with a ladder of vertical ventilation slots and a ribbed underside. Synchron revived it in 2010 and makes it in Italy.
What sizes does the ISOfrane® strap come in?
It is available in 20mm, 22mm, and 24mm lug widths.
Is the ISOfrane® strap made of silicone?
No. It is made from vulcanised natural rubber in Italy, with no silicone, no FKM, and no PFA.
Which watches wore the ISOfrane® strap?
In its original era it was paired with dive watches from makers including Aquastar, Doxa, and Omega.
What buckle options are available?
Three: the forged RS buckle, the stamped IN buckle, and a DLC-coated version. See the ISOfrane® buckle guide for the differences.
