The UnderWarmer® Heated Compression Shirt- Free Ground Shipping On Orders Over $25


(23 customer reviews)

The UnderWarmer® is a single-use, compression fitted base-layer shirt. 8 HEAT PACKS are built-in and will activate within minutes of removing from its packaging. When ready to use, simply remove The UnderWarmer® from its packaging. Upon opening, heat activation begins and will take approximately 30 minutes to reach its maximum temperature of over 100f/38c.



Youth sizes 60-100 lbs
Small Chest: 30 – 34 inches
Medium Chest: 35- 39 inches
Large Chest: 40 – 44 inches
X-Large Chest: 45 – 49 inches


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Additional information

Weight 1 lbs
Dimensions 10.5 × 9.5 × 1.5 in

Large, Medium, Small, XL, Youth

23 reviews for The UnderWarmer® Heated Compression Shirt- Free Ground Shipping On Orders Over $25

  1. Todd **Amazon Review**

    Perfect for hunting in sub-zero weather. This fit right and tight, kept me warm throughout the majority of the day, and the weather was in the negative digits. The only thing is I wish they made pants to legs warm. Great product!

  2. henderson_4 **Amazon Review**

    This was amazing. Bought and wore it for an outdoor flag football tournament I was in. Kept me warm while it was in the low 40’s and flexible and didn’t restrict movement. Stayed warm longer than the 10 hrs. Will definitely buy again at some point.

  3. B whtstone **Amazon Review**

    WORKS GREAT!! Absolutely GREAT to keep warm in hunting season!!!

  4. kim d. **Amazon Review**

    It really works. This was amazing. Went to football game 20 degree and snow. It really worked well never got cold once. I was impressed so worth the money.

  5. Maria **Amazon Review**

    Went to a game at Lambeau Field when it was 8 degrees outside. This vest was a lifesaver! Made a huge difference when I put it on. It fit perfect for me. I wore an under armor cold gear shirt underneath as well as one over the vest, and a medium vest fit perfect.

  6. Frank **Amazon Review**

    Great for sports events! I wear these between an undershirt and my jacket and they really help keep me warm during sporting events. I’m 5’11” 190 and an X-large fits perfect.

  7. calbow **Amazon Review**

    This under warmer is amazing. It does fit tight like a compression shirt and you can rip it if you are rough with it as I tore it taking it off. I am 5’7” and 200 lbs and XL fits like a glove. It is very light material and stretches as it is a one use product. You can reuse it if you put it in an air tight package but I use mine all day. It really does a good job of keeping you warm in cold weather. I put it on over my long underwear and was toasty warm in 28 degree weather with a 15 mph wind. You can wear it as an undershirt but I would only do that if it gets colder than 0 degrees. I bought 6 more and will buy more when I get down to my last two. Fast shipping. Awesome product I met two guys that designed this product at a sports show a couple years ago and they are great guys. Like to see local guys do good. I highly recommend the under warmer

  8. Ashley

    Great product! Exceeded expectations.

  9. Calvin

    These under warmers are fantastic. Awesome product, fast shipping great price. I have used them in a tree stand 25 degrees with a 15 mph wind kept me very warm.

  10. A **Amazon Review**

    This is one of the best purchases I have made this year. I bought 3 and will buy more. They stayed warm for 10 hours. Worked perfectly in Montana shooting college football outside.

  11. Erica

    Keeps me warm in negative windchills!

  12. Linda

    I missed that it was a single use…but I’ll still give it as a gift

  13. Amy **Amazon review**

    These are fantastic for cold football games!!

  14. Jim **Amazon Review**

    I was truly skeptical but now I am a believer!!! This thing is the real deal. It keeps you so incredibly warm. The forecast for the football game was high of 38 with snow flurries. We were also in the nosebleed seats way way up there and the wind was “supposedly” brutal. But I didn’t even need to wear a jacket. Just a shirt, then this vest then a sweatshirt. And was completely comfortable! And we were up there on the nosebleed seats! The wind was crazy! I was so warm! Other people had parkas and blankets and still shivering! Highly highly recommend!!! Our 5 and 9 year olds melted down by second quarter but not because they were cold. They were so warm! I would recommend not wearing it, infact, on your way in to the stadium. All that walking plus the heat from the vest made it too hot! It lasted a long time too. But they are snug so get a bigger size. If you are bigger than the XL size then I would just cut them song the seams and wear it anyway. Since you will be wearing a coat over it usually, it will be secured against you. Need to find a good hand warmer next. Heard so much about those rechargeable vests from friends who told me “only one side of the vest gets warm” or “the charge only lasts 1-2 hours”. These were toasty for 6+ hours and still going strong. I think the description says 8+ hours. You won’t regret it!!

  15. Andrea Melton **Amazon Review**

    Bought this for my daughter who is a cheerleader to wear under her uniform for really cold football games! She loved it and said it kept her body warm! Handy as you just wear it as a vest and the hot packs are evenly distributed. And it’s disposable when done!

  16. Salvatore Pecoraro **Amazon Review**

    This thing is amazing and must have for cold outdoor weather activities!! I have bought these in the past and will continue to do so for cold long days out outdoors. Bought it for the whole family (7 people) kept us nice and warm for a football game. They run small b/c of the way they are made to fit so get the next size up.

  17. Momof3 **Amazon Review**

    Wore these to a football game with the high temp of 18 degrees!! These kept us warm the whole game and were still warm into the evening hours!! Was a noon game! Definitely will purchase again. We could even take our big coats off and we’re still fine!! Very worth the money!

  18. MB **Amazon Review**

    This product deserves 5 stars or more!!! Kept us warm for over 12 hours in single digit temps at an outdoor NFL game. I will never ever leave home without this glorious invention.

  19. Kalyn Denton **Amazon Review**

    Stayed really warm snowboarding!

  20. Mariah

    So warm…and cant even tell you are wearing it under your clothes!

  21. Vernon Davis **Amazon Review**

    It worked well for hunting

  22. Heather **Amazon Review**

    This thing was amazing!! Kept me nice and warm for a football game. Mine is a size large. Will definitely buy again for the next game

  23. Erika Mihalic **Amazon Review**

    Bought 2 for me(S) and my mom(M) and 1 for my son(L) – we had issues as was little snug but my son did not! So I’d say go up a size if female 🙂 But it worked great! Started to get warm within minutes and really felt the heat after about 20-30! We used these for a Christmas Eve football game and it was -20 out! I gotta say, they helped tremendously! I will definitely buy again!!!

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