Learn what makes us great.

It’s more than the best cooling vest, more than the best cooling packs. Its the combination of the two that assures optimum performance.

All of our products are backed by a 60 day money back guarantee.

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UnderCool, it’s a game changer.

What’s the point of owning a cooling vest if it’s bulky and uncomfortable? Get a vest you will actually want to wear. Designed to be worn discreetly underneath your clothes. UnderCool is comfortable and easy to use for every activity, day after day.

not all cooling vests are created equal.

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Slim Profile allows you to wear what you want and keep your cooling vest concealed.

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Lightweight under 2 lbs. helps you keep your energy for the things you want to do.

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4- Way Stretch keeps the cooling packs secure against your skin for optimal cooling.


88% Nylon / 12% Spandex

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Breathable Mesh works with your body's natural cooling methods and whisks sweat away.


Machine Washable so you can use it day after day.

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Adjustable straps keep your UnderCool comfortable and fitted just for you.

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ThermApparel Advice: Sizing and Fit

Making sure your UnderCool fits like a glove will ensure optimal cooling, check your natural waist size at checkout Or get our complimentary measuring guide, the fitkit.

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ThermApparel’s CoolPacks

Not Ice. Not Gel. Our Phase Change Material (PCM) cooling packs fit into pockets designed to conform to your lower back. Keeping the cooling concealed and comfortable. They are easy to use, ready to be frozen right out of the box, no need to soak or “plump” like other vests.

Engineered to work with your body.


Cooling packs freeze at 70F (21C) so you wont cringe from the cold when you put it on.

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works great in dry AND humid conditions


Non-toxic, biodegradable


Completely dry. Not a wet sticky evaporative vest and no condensation.


fastest recharge time


safe to use directly against your skin



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ThermApparel Tip: The fastest way to recharge

You can put your cooling packs in Ice Water to refreeze them even faster than the Fridge or Freezer. It will take less than 20 minutes to fully freeze them this way.

Beat the heat. Without the chill.

Did you know UnderCool cooling packs freeze at 70°F? Keeping you cool but not cold and allowing for lots of ways to refreeze and store.


Store packs in the freezer and they will be a brisk 0°F.

Cooling packs will last 1-3 hours depending on type. Store them here if you are not putting it on right away, taking it to a far off event or you need the extra few minutes of cooling.


Store packs in the fridge and they will be a cool 40°F.

Cooling packs will last 10 minutes less than freezer storage. Store them here most of the time. It will be comfortable enough to put on right away and keep you cool for a long amount of time.

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Store packs in A/C and they will be a cool 68°F

Cooling packs will last 20-30 minutes less than freezer storage. The packs might not even feel cold to the touch but they will stay cool and keep your core cool for 1-2 hours. NOTE: Be Careful they arent melting if your A/C is set higher.

ThermApparels environmental difference.

We use a bio-based PCM which is non-toxic and bio-degradable. A great improvement over older technologies like paraffin PCM and salt hydrate gels.

All plastics used to encapsulate PCM will eventually wear out. Unlike our competitors, ThermApparel offers a recycling program to easily and safely replace worn out Cooling Packs.


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