Starting at $219.99

Please select a product variant.

Free shipping over $50 or more

If we are out of your size, you can order a 3.0 vest here.


This Purchase Includes:

  • 1 UnderCool vest in your choice of color, white or black
  • 2 sets of cooling packs. Your choice of SlimCool or ExtendedCool 
  • Free Shipping Option at Checkout!

UnderCool features:

  • Adjustable straps and 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 1–3 hours depending on cooling pack

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

Size Waist
XXS 20" -  24”

51 cm - 61 cm

Extra Small 25" - 28"

61 cm - 71 cm


29" - 34"

71 cm - 86 cm

35" - 40"

86 cm - 102 cm

41" - 46"

102 cm - 121 cm
Extra Large

47" - 55"

121 cm - 140 cm
XXL 56" - 61" 140 cm - 152 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. 
  • You will wear a size smaller than you think. 

Sizing Guide:

  • Sizing is dependent on natural waist size not bust size.
  • You will wear a smaller size than you think. 

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.