Starting at $169.99

Please select a product variant.

Free shipping over $50 or more

This package includes:

  • 1 UnderCool vest in your choice of color, white or black
  • 1 set of cooling packs - SlimCool or ExtendedCool 
  • Free Shipping Option at Checkout!

UnderCool features:

  • Adjustable straps and a velcro front for the best fit and comfort
  • Wicking fabrics and built-in mesh panels to keep you dry and comfortable
  • Cooling pack pockets along back
  • Cooling relief for up to 1–3 hours* depending on cooling pack type
  • 60-day money back guaranteed

Please review our sizing chart below to ensure the best fit for your UnderCool:

Size Waist
XXS Men 18" - 24"

Men 46 cm - 61 cm


Men 24" - 31"

Men 61 cm - 78 cm

Men 31" - 40"

Men 78 cm - 101 cm

Men 40" - 51"

Men 101 cm - 129 cm
XXL Men 51" - 64" Men 129 cm - 162 cm

Sizing Tips:

  • Sizing is based on your natural waist, not your hips or pant size. 
  • Measure against your skin.
  • Take your measurements in front of a mirror.
  • Make sure your tape measure is level on both sides. 
  • UnderCool needs to fit your body like a glove to give you the best cooling support. 

Men's Sizing Guide:

  • We recommend ordering a size smaller than your usual T-shirt size.
  • (If you wear a large T-shirt, a medium UnderCool will fit best.)
  • Sizing is dependent on your natural waist size, not hip or belt size


1. Stand or sit up
straight and tall.

2. Bend at both sides.
Where you naturally
bend in your natural

3. Measure where you bend.
If you don't bend measure below rib cage but above belly button.

Other Resources:

Cooling Pack Care and Storage Recommendations:

  • When not in use always store Cooling Packs in the solid state, this means the fridge, freezer, or a room less than 70F/21C
  • Cooling packs left in their melted state for extended periods of time will result in rapid aging and reduce the lifespan of the cooling packs.
  • When handled properly packs should last 2-3 years, and our recycling program provides deeply discounted replacement packs.
  • To wash your cooling packs, use warm soapy water in the sink. Do not put them in the washer, dryer, or dishwasher.

Please review our Return and Exchange PolicyWarranty Policy and User Guide.


Consult your doctor or health care professional prior to using this or any cooling products for a medical condition. ThermApparel LLC will not be liable for injuries or damages resulting from the misuse or misapplication of our products.

*Cooling times may vary depending on your level of activity and ambient temperature. 

Please Note:

  • All prices listed in USD
  • International orders: your country’s taxes and duties are NOT included in the price or shipping

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.