Long mornings on the trail require versatile equipment; you’ll be wearing the same stuff under late morning heat at 11AM that you started with in the fog and chill of 5AM.  The fewer wardrobe changes you need, the better – which is why the arm warmer strategy is so popular with ultrarunners.  Merrell’s Dualtrek offers this versatility in a style that’s both comfortable and fashionable; it’s the ultrarunner’s trifecta.

Royal/navy color combo; gray/black also available


  • 100% polyester with Opti-wick moisture management
  • 30+ UPF
  • Stretch mesh body
  • ½-zip collar for ventilation
  • Lycra stash pockets for arm warmer or gel storage
  • MP3 pocket
  • Silicone grip on ends of arm warmers

Donald hard at work – product testing

Merrell Dualtrek Shirt Review

I’m not much of a “form-fitting” guy; I like tops that are cut a little loosely, while providing good sun coverage and preventing chafing or hot spots.  The shirt component of the Dualtrek scores very highly in all those areas, and rides very comfortably during my multi-hour runs.

Temperature regulation is dialed in nicely here as well, keeping you properly equipped in a wide range of temperatures.  The arm warmers provide nice insulation for cool mornings; I’ve worn them in the low 40s, and estimate they’d be still be comfortable into the high 30s.  When the weather heats up, you peel off the arm warmers, and Merrell’s Opti-wick fabric does an outstanding job of moving moisture away from the skin for ventilation.  The zip collar provides even more air movement for hot days, and I’ve worn this shirt comfortably with temperatures in the high 80s.

Arm warmer tucked in side pocket; stitching of internal mp3 player adjacent

The arm warmers stay in place very securely with their silicone grippers, and tuck away into the side pockets of the shirt when you’re done with them.  These side pockets provide adequate storage for arm warmers or gels.  The internal mp3 pocket is nice for keys, but might be on the small side for some media players.

Over-the-thumb arm warmers

Another point about the arm warmers is that they’re the over the thumb kind.  This provides full coverage and prevents exposure when combined with gloves, but makes wearing a watch or GPS tricky.  You either strap the watch over the top of it – which means you have to unstrap it to remove the arm warmer – or strap the watch underneath, where you can’t read it without peeling down the arm warmer.

Good Dualtrek

  • Great temperature regulation in a wide temperature range
  • Outstanding comfort with multi-hour use
  • Very effective ventilation for warm temps
  • The royal/navy blue scheme is pretty good looking, isn’t it?

Bad Dualtrek

  • mp3 pocket could be bigger, or just used as a key pocket
  • I’d prefer a wrist-length arm warmer

Bottom Line: Merrell Dualtrek

If you plan to stay on the trail from “cool and foggy” to “bright and warm” – or vice versa – Merrell’s Dualtrek is a very solid option to serve you well in both conditions.

Buy Now: Merrell Dualtrek at Merrell.com

About Author

Donald is a physical therapist, ultrarunner, barefoot aficionado, and father of three with more than 20 years of experience in endurance sports. When he's not training for ultramarathons, he enjoys hiking or slacklining with his family in Monterey County, CA.

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