One frustrating fact of cooling vests is that they tend to be bulky, clunky, heavy, and most announce their presence like a 6-pound cyst growing out of your neck. People don’t want to stare or ask questions… but then they stare and ask questions. Thermapparel is flipping the script and has designed a vest—the UnderCool—that is virtually completely hidden, weighs less than two pounds, and lasts longer than many of their larger, full-vest competitors. Heck, it's even slimming! Now, to reach these impressive benchmarks there naturally is a bit of give and take in the design, but not as much as one would think.

The UnderCool is ultra lightweight and stretchy, think shear (and comfy) yoga pants, and comes in four sizes (S, M, L, XL), two colors (white is new), cinching at the abdomen with Velcro. Cooling comes from four phase change (PCM) cooling packs that are inserted into the back of the garment—there is no cooling on the chest. We expected this to be a noticeable negative, but in our testing we still felt refreshed. And a huge side benefit of no cooling packs on the chest: there are no cooling packs on the chest. Women (and men) of all chest sizes can wear this comfortably and stealthily.  No lumps, no tell-tale signs of a vest sticking out of collars, no uncomfortable placement of the packs over a bosom. Because the vest uses PCM to cool, they can recharge quickly in a fridge or freezer, and the packs, while cold, are not too cold. The vest is can be worn over a light t-shirt or directly on the skin and, although I have no experience in this department, I suspect it feels a bit like wearing a well-fitted bra. You don’t really notice it.

We tested this vest both indoors and outdoors in a variety of conditions. On a moderately warm day with temps in the lower 80s, the vest lasted about an hour and a half during heavy exercise before its cooling power was fully exhausted (an hour in hotter temps). Not world beating, but solid, especially considering its weight. In the high sun, I did miss somewhat the cooling on the chest that other vests offer. Indoors and under clothes was another story. The vest easily lasted a full two hours. I wore it for an extra hour and it still didn’t feel “hot” or uncomfortable. This makes it ideal for wearing out to dinner, to a movie, to a parent-teacher conference, out gardening, to that neighborhood barbeque, or to that musical you don’t really want to see but your spouse is making you go. You name it. Sports? Absolutely. There may be better options for max cooling during exercise, but to be able to wear this while running (so comfortable and unnoticeable) or under a t-shirt at the gym in full stealth mode is invaluable.

Is the UnderCool a game changer? I’ll say for most MSers, absolutely. The only issue I could pick at, and it is a stretch, is that the cooling packs are hard to insert, but that’s not a biggie because you can toss the entire vest into the freezer and it takes up no more room than a half gallon of ice cream. Indeed, I've never removed them. If you had an extra vest, you could just rotate them throughout the day. Brilliant! (Of course if you are in the office, you’ll need to hit the restroom or close your office door to do the swap.) I’ve tested many vests and few stay in my rotation after my review is complete. This one is a definite keeper and gets ActiveMSers' highest recommendation.

~ Dave Bexfield

Design: 5

Fit: 5

Adjustability: 5

Endurance: 3

Comfort: 5

Convenience: 4

Concealability: 5

Versatility: 5

Sports: 5

Portability: 4

Quality: 5

Cold Sensitivity: 4

Dryness: 5

Weight: 1 lb 11 oz

   It's not about feeling cold. It's about feeling good.   


ThermApparel is a small business making big waves in the heat sensitivity world by designing the first lightweight, comfortable and invisible cooling vest, UnderCool. Check us out online, on our blog, or on FacebookTwitter, PinterestLinkedIn and Instagram.

Please let us know if you have any other questions or ideas in the comments below, we will follow up. You can always reach us via:

Live Chat -  |  Email -  | Phone - 855-232-7233 |  Address: ThermApparel LLC. 40 Franklin St. 4th Floor, Rochester, NY 14620