UnderCool 3
Regular price
$219.99
Regular price
Sale price
$219.99
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per
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Whether you're managing heat sensitivity, MS, lupus, fibromyalgia, POTS, or menopause, or you're an actor, cosplayer, or performer who needs to stay cool under a costume, the UnderCool 3 was built for you.
Lightweight, concealable, and worn discreetly under your clothes, it delivers 1 to 3 hours of dry, consistent cooling with no ice, no condensation, and no bulk. Trusted by thousands across the US for work, play, travel, and everything in between.
- SAY GOODBYE TO UGLY, BULKY VESTS: Our sleek, under-clothing design stays hidden and comfortable. No one will know you're wearing it.
- DO MORE OF WHAT YOU LOVE: 1 to 3 hours of cooling time for your favorite activities. (1 to 2 hours with SlimCool, 2 to 3 hours with ExtendedCool)
- STAY COOL AND DRY: No condensation or soaking wet clothes like ice or evaporative vests. Just dry, consistent cooling.
- KEEP COOL NO MATTER WHAT: Our PCM cooling packs work in both humid and dry heat.
- COMFORTABLE FOR ALL BODY SHAPES: 4-way stretch fabrics and lightweight cooling packs provide a flexible, secure fit.
- EASY TO USE: Recharge your cooling packs in the fridge, freezer, or ice water in 20 to 60 minutes.
Garment Facts:
Mesh: 89% Nylon, 11% Spandex
Cloth: 87% Nylon, 13% Spandex
Care Instructions:
Garment: Machine wash cold with like colors. Do not bleach. Do not use fabric softeners or dryer sheets. Dry flat. Do not iron.
Cooling Packs: Do not machine wash, they will explode...trust us, we've tried, and it's a huge mess. Clean with mild dish soap and water.
FAQ
Q: What size UnderCool cooling vest should I order?
A: Sizing is based on your natural waist measurement, not your shirt, dress, or bra size. Most people wear a smaller size than they expect. For example, if you typically wear a 2XL shirt or have a larger chest, you may only need a Medium UnderCool. The vest is designed to give you a comfortable, snug fit, like a compression garment or Spanx. What matters is your waist, not your cup size or clothing size.
Sizing Tips:
- Find your natural waist. It's below your rib cage but above your belly button.
- Measure against your skin.
- Take your measurements in front of a mirror to make sure the tape is level.
- If you fall between two sizes on the chart, size up.
| Size | Natural Waist (in) | Natural Waist (cm) |
| XXS | 18" to 24" | 46cm to 61cm |
| S | 24" to 31" | 61cm to 78cm |
| M | 31" to 40" | 78cm to 101cm |
| L | 40" to 51" | 101cm to 129cm |
| XXL | 51" to 64" | 129cm to 162cm |
📏 Still have questions? Check our Sizing Guide, jump on live chat, or call us at 585-204-0841. We're happy to help you find your perfect fit.
Q: What's included with the UnderCool 3?
A: One UnderCool 3 cooling garment and your choice of cooling packs (SlimCool or ExtendedCool), in your selected size and color (Black or White). The garment is worn under clothing, and the cooling packs slide into the built-in pockets.
Q: How does the UnderCool 3 work?
A: Think of it like a heat exchanger. The PCM cooling packs sit against your torso, pulling heat out of the blood flowing through vessels close to your skin. Your body then circulates that cooled blood back through your entire system, bringing your core temperature down from the inside out and cooling your from head to toe. Learn more about how our cooling packs work in our cooling pack guide.
Q: How long does the cooling last?
A: Cooling time depends on the pack you choose and your environment:
• SlimCool packs: about 1 to 2 hours per set.
• ExtendedCool packs: about 2 to 3 hours per set.
For longer outings, consider the UnderCool 3 Double Pack Bundle so you can swap sets while one refreezes.
Q: How do I recharge the cooling packs?
A: Simply refreeze and reuse:
• About 20 to 30 minutes in ice water for the fastest turnaround.
• About 40 to 60 minutes in a standard household freezer.
• About 60 minutes in a standard household refrigerator.
Q: Can I wear it under my regular clothes?
A: Yes. That's exactly what it's designed for. The slim, low-profile design fits discreetly under everyday clothing, workwear, and uniforms without visible bulk.
Q: How do I care for the garment?
A: Machine wash cold with like colors. Do not bleach. Do not use fabric softeners or dryer sheets. Dry flat. Do not iron. For the cooling packs, do not machine wash. Clean with mild dish soap and water.
Q: Do you ship to my area, and how quickly will it arrive?
A: If you order before noon Monday through Friday and your items are in stock, your order will ship the same day. We ship worldwide from Rochester, NY, with free shipping available within the USA, plus standard and expedited options at checkout.
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Regular price
$219.99
Regular price
Sale price
$219.99
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SIZE: XXS
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SIZE: S/M/L
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SIZE: XXL
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Please review our sizing chart below to ensure the best fit for your UnderCool
| Size | Natural Waist (in) | Natural Waist (cm) |
| XXS | 18" - 24" | 46cm - 61cm |
| S | 24" - 31" | 61cm - 78cm |
| M | 31" - 40" | 78cm - 101cm |
| L | 40" - 51" | 101cm - 129cm |
| XXL | 51" - 64" | 129cm - 162cm |
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Sizing Tips:
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Reuse 1000’s of Times
Cooling Pack Care:
Washing Instructions:
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Non-Toxic Bio-Based Phase Change Material (PCM) |
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Freezes at 70F (21C) so its safe against the skin. Unlike Ice. |
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Works in humid & dry conditions |
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Cooling lasts 1-3 hours depending on cooling pack type & environmental conditions |
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Won’t condensate so you will stay dry |
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Recharges in 15-60 minutes |
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Can be used 1000’s of times for around 3 years |
What clients say
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NOW I CAN enjoy all that Walt Disney World has to offer without worrying about the walking or the weather!
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My UnderCool vest has allowed me to golf in warmer weather that would normally be too hot for me to play due to my MS.
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"MS is such a tiring disease. I was a very physical person, I was a physical educator, I was a coach, outdoor person and with climate change, Michigan has become very warm. I couldn't go outside. I couldn't last, I would go outside for 10 - 20 minutes doing something and I would be totally exhausted. The ThermApparel Cooling Vest made a world of difference. A huge world of difference. It gave me my life back
Why We're Better
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Evaporative Cooling
- Doesn't work in humidity
- Cools your skin, NOT your core directly
- Lightweight & Flexible
- Must be wet
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Our PCM Cooling System
- Works in any climate
- Cools your core body temp
- Lightweight & flexible
- Dry conformal cooling
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Gel & Ice Cooling
- Works in any climate
- Too cold for direct skin contact
- Heavy & rigid
- Wet from condensation