Zoot is primarily a running products company specializing in shoes. Their line of Sport T-shirts are in fact very compatible with other activities, such as backpacking and hiking. I used the Ultra Run Icefil shirt as a base layer for backpacking in the often-changing climate of the Pacific Northwest. It definitely provided the cooling effect one needs on a long steep trail or a flat beach hike on a sunny day.

Ultra Run IcefilThe Ultra Run Icefil is very lightweight and fits snug and close, allowing the patented Icefil technology to absorb body moisture and reduce body temperature. Microdenier polyester yarns create a moisture-wicking textile that pulls moisture away from your skin and helps it evaporate quickly. Zoot claims it will reduce skin temperatures by 5.4 degrees. I did not put a thermometer on my skin to test the degree of heat reduction, but I can attest it felt cooler even when I with heavy exertion with a full pack uphill in the sun. When I stopped at camp for the evening, I watched to see how long it took to dry. I was impressed that it dried very quickly and I did not chill much while it evaporated away the excess moisture.

Some base layer garments have seams that are rough or abrasive especially when you wear a pack and shoulder straps run across seams. The Zoot Ultra Run Icefil is soft and comfortable with no hard or abrasive seams or edges. I like the bright color selections in green or orange, but for those with more conservative tastes they also offer black or pewter

The company does not make any claims about its heat retention qualities as it is intended to cool, but for backpackers, heat retention and quick drying are important qualities. I was surprised to feel a fair amount of heat retention even while just wearing the Ultra Run Icefil once it was dry. Even at snow level, in the Tee and hiking pants I was not uncomfortably cold.

Ultra Run IcefilBackpackers are always concerned about weight we carry and in the clothes we wear. This lightweight Ultra Run Icefil is only 3.3 ounces which makes it a good choice for the ultra-light backpacking community.

This product has an added benefit in that it blocks sun rays to UPF 50. This will be of benefit to any backpacker who lives or hikes in a sunny or hot environment. It can be especially good for those of us in climes where we aren’t regularly exposed to sunlight and find ourselves out for a hike on a hot sunny summer day.

Overall, I am very satisfied with the product and would highly recommend it to anyone who wants a high quality, durable, breathable, heat reducing base layer or summer tee. You will find you use it a lot if you live in a hot or sunny climate or for any time you run, exercise, hike or backpack. I anticipate using it almost anytime I backpack for its wicking and fast drying qualities.


  • Stretch fabric
  • Machine Washable
  • Very lightweight
  • Wicking and cooling fabric
  • UPF 50 Sunscreen
  • Snug but not tight fit


  • Cannot be Machine Dried.

Tech Specs

  • Icefil® combines Xylitol and thermal radiation nano technology, reducing skin temperature up to 5.4ºF/3º
  • Icefil® mesh for enhanced ventilation and cooling
  • Flatlock stitch construction ensures next-to-skin comfort and minimizes chafing
  • Dropped back hem for enhanced coverage
  • 27″ (68.6cm) length
  • 3.3Oz. Weight
  • Cost About $40
  • 50+ UPF sun protection
  • Moisture-wicking textile


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