Video transcript:

"Will a cooling vest work for you? Yes. Because of cooling vest cools the blood on the skin because it cools that skin down. The blood circulates through the body keeping your core temperature down. What that does? It helps keep that heart rate low, which fights that fatigue that awful fatigue that you feel the next day after you've been out at the pool all day. You know that feeling? That's because you got too hot. Wear your vest. Help keep your core cool. Fight the fatigue."


A cooling vest works by lowering or stabilizing body temperature. This helps make exposure to uncomfortable temperatures more bearable. Cooling vests are used by people suffering from heat sensitivity due to sports, industrial applications, medications, and individuals suffering from multiple sclerosis, and other neurological disorders.

There are 5 different types of cooling vests.

  • Evaporative
  • Ice-chilled
  • Cool flow
  • Gel
  • PCM (phase change material) (ThermApparel's Cooling Vest)

ThermApparel's UnderCool Cooling Vest works by using PCM (Phase Change Material) Cooling Packs. PCMs are substances that absorb and release thermal energy during the process of melting and freezing. What does that mean? Simply, they act as a heat sink to absorb your body heat slowly over time to keep you cool and comfortable, even in humid environments. Check out the Tech Page for the nitty gritty

ThermApparel uses a non-toxic bio-based PCM that outperforms paraffin, salt hydrates, gel, and ice in a number of areas. Long-term stability, and safe handling, sourced from recyclable materials, won't get you wet or burn your skin. Our lightweight and flexible PCM cooling packs are reusable and can be recharged again and again and again.





UnderCool is secured in the front with an easy hook-and-loop closure for easy on and off and adjustable straps for the best fit.

UnderCool comes in 5 sizes XXS, S, M, L, and XXL to fit a wide variety of body shapes and sizes, because "one size fits all" really isn't true. UnderCool needs to fit your body like a glove to give you the best cooling support. We recommend going with a size of a super tight undershirt for men or camisole women. The best part, sizing is not dependent on your bust size... Yay for women!!... sizing is dependent on your natural waist.

All our vest garments are made of comfortable spandex (think comfy yoga pants) and mesh panels to keep you cool and dry for maximum breathability. Cloth: 87% Nylon / 13% Spandex Mesh: 89% Nylon / 11% Spandex

Not sure where your natural waist is or how to get the correct sizing? If you bend to the side, you will crease in the middle of your body; this is your natural waist. That's where you want to take your waist measurement. Then check our handy sizing guide and order the correct UnderCool for you.

Have questions about sizing or ordering? Call us at 855-232-7233. We really do answer the phone! We are in the office 9-4:30 EST. If we don't pick up please a message, we will call you back. You can also email us at, or you can live chat with us online.