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Outdoor Research Enigma Half Zip

rated 4.5 of 5 stars
photo: Outdoor Research Enigma Half Zip base layer top

The Enigma Half Zip is a base layer that places wicking moisture and drying quickly at a premium. That's a little unusual for a shirt that's partially made of merino wool, but in this case, the blend is 88 percent synthetic, 12 percent wool. Choose this shirt for high-sweat, high-output activities; consider a thicker/heavier base layer for bitter cold. The relatively light fabric and great moisture management makes this an attractive layer year-round until it's so warm that you're better off in short sleeves.


  • Moisture handling
  • Comfort
  • Great design


  • There are warmer options



Outdoor Research's Enigma Half Zip is a long-sleeved base layer that has an unusual blend of synthetic and wool—88 percent polyester, 12 percent wool, woven together in the same yarn. Check out my recent reviews of the Enigma Bottoms and Boxer Briefs.

The synthetic fabric is Outdoor Research's DriRelease E.C.O., "Environmentally Correct Origins," and the wool is merino. As FYI, DriRelease E.C.O. is made from 100 percent post-consumer recycled PET, the material used to make plastic bottles and containers, and blended with natural fibers like wool or cotton—in this case, with merino wool. 

The shirt feels light because the fabric is fairly lightweight for a cold weather base layer. As you can see, the half-zip is relatively long, 12 inches, which is nice for warmer days where you may want to vent some heat. The fabric is pretty stretchy. The long sleeves have thumb loops that are helpful for pulling layers on while you're hiking. 





The Enigma half zip runs true to size—you can rely on Outdoor Research's size chart that runs from S to XXL for men and XS through XL for women—and the stretchy fabric means it will fit a wide range of body types. Coincidentally, I lost fifteen pounds during the testing period, so it's a bit looser today than it was when it arrived. The zip neck doesn't feel confining. (Outdoor Research also has the Enigma Crew top for men and women, if you prefer that.)

As you can see, there are some seams running across the front and back over the shoulders and in the middle of the arm; they're flat and didn't chafe or irritate me. Also, the shoulder seams are placed so they don't sit directly under the weight-bearing part of backpack shoulder straps, which was thoughtful. Outdoor Research clearly doesn't think having lots of seams is a problem.

The fabric itself feels soft, so it's easy to wear next to the skin. I think the wool blended in gives the fabric a slightly softer feel and a little more substance than a 100 percent synthetic layer. Overall, the light weight, soft feel, and flat seams make it particularly good as a next-to-skin base layer.

The stretchiness means awesome range of motion, so for scrambling, climbing, Nordic skiing, and other pursuits where you need very good range of motion, this is a good choice.  


On the spectrum of base layers, I would put this somewhere in the middle for keeping you warm. In this respect, it functions much more like a synthetic than a layer with some wool, and more like an all-season layer than a winter layer, unless you're doing something very high-output like running or nordic skiing. I have long-sleeved wool and wool blend base layers (other than this one) from three different sources, and they are all meaningfully warmer than this, but they are all or mostly wool, unlike the Enigma.

On the other hand, this provides a little more insulation than a thin synthetic shirt, but not as much warmth as beefier synthetic layers. For example, I wore this shirt alone under a wind shell (not a waterproof/breathable) on a hike where the temperatures were in the low 20s Fahrenheit and the wind was blowing relatively hard, and it was not enough to keep my core warm, despite some reasonably strenuous sections of the hike. I was much happier after I stopped and added a fleece vest over the Enigma. 

On the plus side, though, this layer is comfortable to wear into much warmer weather than other layers with more wool. We had a peculiarly warm weekend where temps were in the 60s this winter; I wore this shirt alone on a couple of day hikes, and it felt great on the warm days. For cooler to cold weather, I tended to add a shell, a fleece, or a vest over the top of the Enigma Half Zip. 


This is where the Enigma tops and bottoms excel. This became a favorite for harder hikes because it does such a great job wicking sweat away and drying quickly when I'm done. On several early morning walks and hikes, I got back into a car or arrived home and forgot to take this off because it dried while I wore it. The mostly-synthetic blend definitely helps it handle moisture better than any wool layer I own, even lightweight, 150-weight merino shirts.  

Because this shirt does so well at handling sweat and wet, I ended up wearing it with many different combinations of other layers—light and very thick fleece vests and jackets, under a wind shell, under a more robust Gore-tex shell, and under a soft shell jacket. I also reached for it when I expected to be walking or hiking in the rain. 

20200208_104444.jpgThese were taken at the end of a healthy (5-mile) walk on a relatively warmer day, after which I screwed around with our puppy for a while. The shirt is basically dry. 



Wool, even blended, needs a little bit of attention. I laundered this shirt periodically (the wool blend is very good at keeping odor to a minimum) and either dried it hanging on a clothes rack or  gave it a limited run in a dryer, then let it hang and damp dry. Manufacturer's instructions say this should be line dried.

Any fabric that's this thin should be a bit of a durability concern. This is another area where the shirt performs more like a synthetic layer, because 100 percent merino wool or blends that are 80-90 percent wool tend to pill and get small holes a lot more quickly than synthetics. So far, the key wear points—under a backpack shoulder strap and at the back, where the hem is under a hip belt—aren't showing any damage or visible wear. 


The wool blend is helpful in this category, because this shirt does a better job repelling odor than many synthetic layers I wear. To test the odor-fighting properties, I went about ten days without washing the shirt, wore it several times on hikes and walks during that period of time. It had gotten to the point that it was worth cleaning, but the odor wasn't bad, certainly not overwhelming. 100 percent wool does a better job with odor than this shirt, for what it's worth.  



Where we live in Maryland, the temperature rarely falls below high teens, even in the middle of the winter. I wore this shirt on most hikes and walks I took over two to three months, in temperatures ranging from high teens to low 60s. For the most part, I wore the Enigma Half Zip under a soft or hard shell on its own, if the temps were closer to 40, or with an insulating layer and/or a shell when the temperature was in teens through mid-30s.

It worked particularly well under a soft shell, which does a better job expelling moisture than most hard shells, and under fleece jackets or vests that don't have wind block layers and that also do well dealing with sweat. I'm wearing it in the photo above under Patagonia's Nano Air Hoody, when it was about 35 degrees on that hike.

It was reasonably common, when I wore the Enigma under a couple of fleece layers I own, to get a significant amount of frozen moisture on the outside of the fleece after a decent hike. 

I often wore the Enigma shirt under a backpack, but most of the time, I was wearing a shell or other layer on top—keep that in mind when assessing my review about how well this shirt does with wear and tear. 


The Enigma Half Zip is a lighter-weight layer, very desirable for hiking, cycling, and other activities when you're working hard and want a base layer next to your skin that does a good job wicking moisture. Consider this to be a three-season layer (except for the heat of summer) due to its light weight. Given its light weight and comfortable feel, I liked this shirt a lot and highly recommend it.  


I wore this shirt on dozens of hikes and walks over a period of 2-3 months, in winter weather in the mid-Atlantic.

Source: received for testing via the Trailspace Review Corps (Sample for review and testing provided by Outdoor Research)

About the Author

Andrew Friedman is a New Hampshire native who loves the Presidentials and spent his college summers guiding trips in the Adirondack High Peaks. He loved introducing his children to hiking and the outdoors. In addition to New England and the Adirondacks, he has hiked the shores of the Great Lakes, the Tetons, a number of California's state and national parks, the Albanian Alps, and trails in India, Asia, and the Middle East. Andrew logged his first review on Trailspace in 2007 and joined the Trailspace Review Corps in 2011. Andrew lives and works in the DC metro area.

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Price MSRP: $79.00
Historic Range: $43.42-$79.00
Weight 7.8 oz / 221 g
Fit Next-To-Skin Fit
Center Back Length 29.5 in / 75 cm
Fabric driRelease 88% recycled polyester, 12% wool
Price MSRP: $79.00
Historic Range: $42.30-$79.00
Weight 6.7 oz / 190 g
Fit Next-To-Skin Fit
Center Back Length 28.5 in / 72 cm
Fabric driRelease 88% recycled polyester, 12% wool
Product Details from Outdoor Research »

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