Order before 2pm for same day turnaround!

better health through cooling for multiple sclerosis, lupus, diabetes, and dysautonomia


love your neighbor as yourself

ThermApparel Adventure Bundle
Med. Black/White, ExtendedCool Packs

Why cooling is important?

Our bodies are always producing heat. It’s up to our heart and blood vessels to get that heat away from our core organs. Using a cooling vest makes life easier on your heart to keep you safe and give you more energy for what you care about.

benefits of undercool

  • Fight fatigue
  • Beat cog fog
  • Enable exercise
  • Explore the world

UnderCool works by absorbing heat away from your body in a concealable, lightweight, 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 the perfect temperature to work with your bodies natural cooling system.

easy to use, whenever and wherever

Cool it.

Keep your UnderCool in the 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.

Do more of what you love; walk the dog, spend time with family, enjoy your hobbies.

Trust in Us! 60 days to try.

If a vest remains in your closet because you are too embarrassed to wear it, well, then it is of zero help. Invest in your health and happiness with a durable, comfortable cooling vest. To prove it ThermApparel has a 60 day exchange/return policy for a full refund less shipping provided the vest is returned in like-new condition.

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.

“I was able to enjoy Walt Disney World.”


Recipient of Presidential Service Award and 2
time Congressional Medal of Service Award

ThermApparel Festival Bundle
Medium White, ExtendedCool Packs

ThermApparel believes in leveraging creativity, empathy, and dignity of the human spirit to help others break barriers related to heat sensitivity. We strive to provide independence and a more active lifestyle to people living with Multiple Sclerosis, Lupus, Dysautomia, and POTS.

Don’t just take our word for it...

Financial Assistance

You know what is just as bad as heat stress? Financial Stress. So we have teamed up with leading non-profit organizations to help you out when you need it. Check out the list here.

“Now I can golf in warmer weather”


ThermApparel UnderCool
Medium Black, SlimCool Packs

not all Cooling Vests are created equal




Slim Fitting, Easy Fasten

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


1- 3 Hours Cooling Time

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


Machine Washable

Mild detergent, cold water, air dry


Safe Effective Cooling Temperature

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


Lightweight, Comfortable, Reusable

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


Earth Friendly

Non-Toxic and Biodegradable cooling packs are safe directly against the skin. Our packs come with our unique recycling program.


Did you know?

UnderCool cooling packs freeze at 70F working with your body to improve cooling. Other products which use Ice or colder PCMS for cooling can cause blood vessels to 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.

“Now I can continue working"


Earning a Ph.D.

ThermApparel UnderCool
XS Black, ExtendedCool Packs

shop now

“Everyone has heat sensitivity, it’s just a matter of the degree”

  • Do you stay inside most days when it’s over 80F?
  • Does humidity affect you more than the temperature?
  • Does a hot shower make you tired and weak?
  • Does strenuous exercise take days to recover from?

YOU have
heat sensitivity!

learn more

frequently asked questions

1. Does insurance cover ThermApparel Cooling Vests or can I get financial assistance?

Cooling vests are currently not typically covered by insurance. They don't think they are medically necessary. ...we know, we think it's silly too. Ultimately it depends on your insurance company and your individual plan. If you want to try the insurance route we have tips and suggestions on our insurance page.

If you need financial assistance for a vest there are many organizations and foundations that might be able to help especially if you have MS, Lupus, Pots or Fibromyalgia. Check out our list of partners to see whose cooling programs we participate in.

2. 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.

3. 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.

4. What if the UnderCool doesn't work for me? Can I return or exchange it?

Yes. We have a 60 day return/exchange policy.

5. How do I recharge the 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.


“Now I can spend more time on the water”


Raised over $95k in 11 years for Walk MS
Rochester with my team Alecks

ThermApparel Adventure Bundle
Small White, ExtendedCool Packs

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 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.