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j2-baselayer products

J2 Baselayer

The J2 baselayer was developed for the US Deep Caving Team’s 2013 expedition to explore Cheve Cave System in Mexico. With excellent anti-microbial performance thanks to the use of silver ion technology, and outstanding wicking from a unique fabric, it is designed for extended use under a drysuit.

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Performance in Extremes

Keeping the skin dry can be critical to success, whether it is staying warm, or preventing infections. The J2 base layer was designed to wick perspiration away from the skin and maintain a dry zone next to the skin. Air is a better insulator than water and consequently, the baselayer ensures better thermal protection.

The J2 baselayer system takes this performance further with tried and tested anti-microbial silver ions embedded within the fibres of the fabric. This enables long, repetitive wear without the risk of skin infections developing – something which was critical on the J2 expedition.


“Thanks again for all your support. Your products saved our lives, I spent three weeks in a row once, 24h/day without any problems during [the 2013] expedition.” Marcin Gala – lead diver on the 2009 and 2013 J2 expedition.

“The performance was unbelievable” Phil Short – lead diver on the 2013 J2 expedition

“It's really a wonderful thing when a promising article of gear (or clothing) lives up to and exceeds its expectations.” Bill Stone – expedition leader

Products in the Range

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Men’s J2 Top

A simple, close fitting design with flat seams for next to skin comfort offers the perfect solution under any drysuit underwear.

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Men’s J2 Leggings

With colour-coordinated comfort zip, the top is not only easy to don, it has good aesthetics and is extremely comfortable thanks to excellent all-way stretch fabric and flat seams.

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Women’s J2 Top

With colour-coordinated comfort zip, the top is not only easy to don, it has good aesthetics and is extremely comfortable thanks to excellent all-way stretch fabric and flat seams.

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Women’s J2 Leggings

Comfortable soft waistband and flat seams maximise next to skin comfort.

J2 Features

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Silver ions are incorporated into the fibres when they are manufactured, ensuring that the bacteriostatic and ant-fungal properties of the fabric last. This cannot be washed off. The silver ions prevent the formation of bacterial cell membranes, preventing most bacteria from growing in the fibres of the garment. However, this will not adversely affect the naturally occurring bacteria on the skin itself.

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Performance When Wet

The J2 wicking performance also comes into its own when the fabric gets wet. Water is wicked away from the skin, and with the right combination of drysuit underwear, further away though the fibres of the undersuit. Even in the event of a suit flood, the J2 will retain some of its performance.

J2 - Fast Wicking Baselayer

The unique knit of the J2 fabric maximises the air next to the skin whilst providing good contact points for moisture from perspiration to be wicked away. This wicking action is a mechanical process and will last for the lifetime of the garment.

new yorker article

New Yorker Article

The J2 Expedition

Fourth Element Team Diver Phil Short, was a lead diver on the J2 expedition – read fourth element Director Jim Standing’s article on the expedition here…

1000 hours under the Earth

If Phil Short was a surfer, he’d be Kelly Slater. If he was a footballer, we’d talk about him like we do about David Beckham (he has the tattoos to match). If he was a sprinter, Usain Bolt would be looking for him over his shoulder. But he is none of those things. What he is, is one of the most accomplished divers and explorers of his generation and he pushes the limits of technology and human physiology in the pursuit of his dreams. In 2013, he was the lead diver on the most ambitious cave diving project yet attempted, and he returned from the bowels of the earth in the deepest cave system in the Western Hemisphere.

Phil Short is skinny – painfully so. He’s just returned from one of the most demanding cave diving projects ever attempted, and he is badly in need of rest. It’s late Spring 2013, and he is back after 45 days exploring the remote J2 cave system in Mexico, 8kg lighter than when he departed. Phil is, quite simply, exhausted.

“During the course of five trips I was underground for more than 1000 hours with 42 nights spent below the surface of the Earth.” Phil says.

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“Why?” I ask, not quite sure that I would really understand the motivation that leads people to spend that amount of time away from daylight. But when it comes, the answer is remarkably prosaic and I half hope he’ll follow it with “innit”.Clearly, understanding the mentality of modern day explorers who drive themselves to ever more Herculean exploits is not really about understanding their objectives. There is much more to be understood by appreciating the process. I knew what the team had been planning of course: I had been included in some of the early discussions as they realised that in order to undertake this expedition they would need more specialist equipment than was commercially available and this extended as far as their clothing. Phil had approached fourth element on behalf of the team to come up with a solution for the problem that had occurred the last time that explorers had visited this cave system. “We need to travel as efficiently as possible, and all our gear must pack up in to the smallest possible spaces. There is no spare room for much in the way of clothing so we will be wearing the gear the whole time we are down there.” Phil’s tone revealed that he was revelling in the privations to come, as a measure of the extreme nature of the exped. “Last time, the divers all got horrendous skin infections due to wearing the same underwear 24 hours a day for 20 days. I was hoping fourth element can help prevent that happening this time.”

Beyond this awful thought, the objectives of the expedition were as basic as most - to continue exploration: the 2009 expedition had made significant progress in exploring this incredibly deep system, and laid line into the fourth sump. The 2013 crew planned to go further… So, the project was not dissimilar to countless others, many of which we have been asked to support, but there were significant differences, one of these was the cave itself. It is part of the Cheve Cave system – the deepest in the Western Hemisphere, extensively explored by many caving expeditions eager to find the route that connects these caves with the resurgence in Santo Domingo Canyon to establish it as the deepest cave system in the world. Entering the J2 cave at the “Last Bash” entrance offered the team the best chance to do just that. The extent to which this vast network has been explored, and the logistics involved with it mean that few would argue with the notion that this is at the limit of human endurance, and is widely recognised as the most remote point yet reached on Earth by man. Who wouldn’t want to be able to say that they had been somewhere like that?

Another reason this expedition stood out was the personnel, and of this international team, two in particular: Phil Short and Bill Stone. Bill, the team leader, has spent much of his career designing space exploration products for NASA. He is also responsible for some of the major developments in diving technology and the demands of exploring this cave system have driven many of these breakthroughs. He practically invented the Poseidon Discovery MK6 rebreather in order to explore J2 beyond the limits reached in earlier expeditions. His dedication to this cave system and the technological breakthroughs needed to explore it are what make any of this possible and what compelled us to get involved.

The project’s statistics are pretty compelling: altitude of the cave entrance, 3000m, vertical descent of the cave – 1.2 km, horizontal distance covered – 12km. Fifty 25 kilo containers of equipment were lugged through an obstacle course of mud and flooded passageways. Rebreathers were then assembled for the exploration of what at this point was thought to be the end of the line, literally. However, 600m into the sump laying nearly 200m of new line (to put this into perspective – this alone is no mean feat in cave diving terms - to do it several miles underground is amazing), Phil Short and Polish caving expert Marcin Gala reached a breakthrough: the end of the sump. They removed their helmets and hoods in dry cave to hear the roar of a waterfall heralding vertical tunnel. Could this be the passage which descended far enough to connect with one of the other systems?

They descended the waterfall and began to explore virgin cave for another kilometre – another astonishing statistic to add to the list – until the cave began to dwindle in size before finally ending in a calcite-plugged impasse where the water drained through holes too small for the cavers to continue.

Simultaneously elated and frustrated, with heads full of questions, Marcin and Phil retraced their steps, dived back through sump 4, disassembled the rebreathers, packed them up and began the process of transporting the gear back through the myriad tunnels to base camp, and eventually, back into the light, the only two men to have seen what was definitely the most remote point yet visited on Planet Earth.

I return to the question of why in my conversation with Phil, waiting for something verbose and scientifically inspiring. A three word answer is all it takes.

“For the adventure” he smiles simply.

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Image Gallery

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All images were taken by members of the J2 expedition team: Marcin Gala, Kasia Biernacka

Useful Information

J2 Size Charts

Use the table below as a guide to help select which size J2 Baselayer best suits your body type.

If you require any further assistance/advice please don't hesitate to contact us.

Mens Sizes

Sizes Height Chest Waist Inside Leg*
Inches Cm Inches Cm Inches Cm Inches Cm
S 5'7"-5'10" 170-178 34-38" 86-96 27-30.5" 68-78 31-32.5" 79-83
M 5'9"-6'0" 175.5-183 38-41.5" 96-106 30.5-34.5" 78-88 32.5-34" 82-86
L 5'11"-6'2" 180.5-188 41.5-45.5" 106-116 34.5-38.5" 88-98 33.5-35" 85-89
XL 6'1"-6'4" 185.5-193 45.5-49.5" 116-126 38.5-42.5" 98-108 34.5-36" 88-92
XXL 6'3"-6'6" 190.5-198 49.5-53.5" 126-136 42.5-46.5" 108-118 36-37.5" 91-95

Please note all womens sizes are in UK sizes. See the chart at the bottom of the page for a comparison reference.

Womens Sizes

Sizes UK Sizes USA Height Chest Waist Hips Inside Leg*
Inches Cm Inches Cm Inches Cm Inches Cm Inches Cm
8 6 5'4"-5'7" 162.5-170 29 -32.5" 74-82 22.5-25.5" 57-65 32.5-35.5" 82-90 28.5-30.5" 73-77
10 8 5'5"-5'8" 165-173 31.5-34.5" 80-88 25-28" 63-71 34.5-38" 88-96 29.5-31" 75-79
12 10 5'6"-5'9" 167.5-175 34-37" 86-94 27-30.5" 69-77 37-40" 94-102 30.5-32" 77-81
14 12 5''7"-5'10" 170-178 36-39.5" 92-100 29.5-32.5" 75-83 39.5-42.5" 100-108 31-32.5" 79-83
16 14 5'8"-5'11" 172.5-180 38.5-41.5" 98-106 32-35" 81-89 41.5-45" 106-114 32-33.5" 81-85
18 16 5'8"-5'11" 172.5-180 41-44" 104 -112 34.5-37.5" 87-95 44-47" 112-120 32-33.5" 81-85
20 18 5'8"-5'11" 172.5-180 43.5-46.5" 110-118 36.5-40" 93-101 46.5-49.5" 118-126 32-33.5" 81-85

Comparison chart

UK USA France Germany Italy
6 4 34 32 38
8 6 36 34 40
10 8 38 36 42
12 10 40 38 44
14 12 42 40 46
16 14 44 42 48
18 16 46 44 50
20 18 48 46 52