Best Savings of the Year!

$50 off Bundles 

from the stage to
the forest,
cooling to keep you


benefits of UnderCool

  • Stay on schedule
  • Reduce risk
  • Maintain focus
  • Improve personal life

UnderCool works by absorbing heat away from your body in a lightweight, long lasting, and comfortable cooling vest.

how does it do that?

Unique Garment Design

UnderCool vest uses 4 way stretch for a snug fit and strategically placed cooling packs for comfort and concealability.


Advanced Cooling Technology

Our cooling packs take into account human physiology, freezing at perfect temperature to cool your core and work with your bodies natural cooling system.


more ways to use

Cool it.

Keep your UnderCool in a cooler, fridge, or freezer to grab and go whenever you need it. 

Wear it.

Slip the cooling packs into the vest and wear under (or over) your favorite outer layer of clothing.

Love it.

Stay safe, stay focused, and feel better after work.


Womens and Mens Sizing

Use your preferred shop to get the best measurements for your perfect fit. The products are the same in each shop. To get the maximum cooling effect from a vest, it should fit snugly around your body.

“This vest adds almost nothing to the cookie zone”

Santa Ed

Helping fellow Santa's and Mrs.Claus's
spread the Christmas Spirit
through extraordinary experiences.

ThermApparel Adventure Bundle
Lrg. White/White, ExtendedCool Packs

Is it comfortable to wear while seated?

YES! Pilots and race car drivers have worn our product with great results. It's so comfortable, most people forget they have it on.

Santa's wear our product when they are talking to kids in the hot malls.

Whether your out in the heat. Or under hot lights. No Compromises Needed.

Long Lasting



1 - 3 hours Cooling Time

SlimCool Packs 1-2 hours cooling time.
ExtendedCool Packs 2-3 hours cooling time.


Slim Fitting, Easily Transportable

7 sizes and 2 colors. Adjusts to fit a wide variety of body shapes and sizes. No zippers or snaps.


Machine Washable

Mild detergent, cold water, air dry


Lightweight, Comfortable, Reusable

SlimCool Packs Weight - 1.3 lbs.
ExtendedCool Packs Weight - 1.9 lbs.


Safe Effective Cooling Temperature

Cooling Packs freeze at 70F/21C. Not too cold or too hot. Keeping you comfortable and works with your bodies natural cooling.


4 Way Stretch Fabrics

Provide comfort and optimal cooling


Did you know?

Cooling vests CAN be too cold. When using Ice for cooling our blood vessels constrict. This prevents the cooling from reaching other parts of our body, and can cause your core to actually heat up by preventing the flow of blood to your extremeties. UnderCool packs freeze at 70F working with your body to improve cooling.

As Seen on TV

Learn who is secretly using our cooling vest under their costumes

how to recharge and cool on site.

Did you know UnderCool cooling packs freeze at 70°F. Allowing for lots of ways to refreeze and store.

Refreeze quickly in a cooler with ice water for a cool 32°F / 0°C

Keep a cooler of ice water handy for a quick 15-20 min recharge.


Store  in the freezer and they will be a brisk 0°F / -17°C

Cooling Packs refreeze in 45 min. Safe to store in freezer for long term, if not wearing right away, taking to an event or need the extra few minutes of cooling.


Store in the fridge and they will be a cool 40°F / 4°C

Cooling Packs refreeze in 60 min. Safe to store in fridge for long term. Cooling Packs will be at a comfortable temperature to put on right away.


Store in A/C and they will be a cool 68°F / 20°C

Cooling Packs refreeze in 8-12 hours. They may not feel cold to the touch but they are working to keep your core cool.


“I enjoy working at my pub more with my cooling vest”


Proud owner of Coach and Horse Pub

ThermApparel Adventure Bundle
Small White, ExtendedCool Packs


Helpful Hint

Find yourself dreading putting on a FR-R-E-AZING cooling vest. If you store your UnderCool in the fridge or even in an air conditioned room (68F or below) your packs will stay frozen and you wont get that uncomfortable chill.

frequently asked questions

1. How long will an UnderCool keep me cool ?

Cooling packs will stay cold for 1-3 hours depending on your level of activity and the ambient temperature. ExtendedCool Cooling Packs last 2-3 hours. SlimCool Cooling Packs last 1-2 hours. To learn more about the cooling packs check out our tech page.

2. Can I wear UnderCool under a costume?

Yes! The concealable feature of the cooling packs being located on the lower back makes it the ideal cooling option for tightfitting costumes, singers, and actors. You might have seen UnderCool Cooling Vests in action and didn’t even know it. UnderCool Cooling Vests have been used on major TV shows.

3. How do I find my correct size?

Currently UnderCool comes in 7 sizes XXS - XXL to fit a wide variety of body shapes and sizes, because "one size fits all" really isn't true. UnderCool should fit your body like a glove to give you the best cooling support.

Sizing is dependent on your natural waist measurement, not your bust, shirt or pant size. You will most likely wear a vest smaller than what you think. Not sure where your natural waist is or how to get the correct sizing? Check our sizing guide to get the correct UnderCool for you.

4. How do I recharge the Cooling Packs?

Our Cooling packs are the easiest and fastest to recharge for their next use. The packs can refreeze in ice water in 20 min, in the freezer in 40 min, and in the fridge in 60 min. Nothing else from you is required. To learn more about the cooling packs check out our tech page.

5. Will my UnderCool “sweat or feel “wet” while wearing it?

The PCM in our Cooling Packs is sealed in heavy-duty industrial plastic. While the PCM does melt as it absorbs heat, the liquid PCM is kept within the Cooling Packs. The packs will not melt like ice and gel packs which can condensate and get you wet or cause wet spots on your clothing.

If you experience any wetness, remove the packs as this could be a leak. The PCM is USDA-certified non-toxic, biodegradable, and will not harm you but may stain your clothes. Check out our cleaning blog for more information.


four things to decide before you buy

bundle your order and save.

Upgrade from an UnderCool to a Festival or Adventure to save on extra sets of Cooling Packs or an extra Vest Garment.


white or black, pick your color

If you wear more dark clothing order black. If you wear more light clothing order white. If you still can't decide, buy an Adventure and get both colors!


correct fit = best cooling

A snug fit ensures optimal cooling. With 7 sizes XXS - XXL, you will be sure to find you perfect size.


cooling time vs. weight

ThermApparel offers 2 cooling pack options. ExtendedCool lasts 2-3 hours and weighs 1.9 lbs. SlimCool lasts 1-2 hours and weighs 1.3 lbs.


Questions about our vests or shipping? Reach out to the ThermApparel team toll-free at 855-232-7233, write to us through our website’s contact form or chat with us via live chat. We always respond because, otherwise, that wouldn't be cool.