The Under Armour Base 4.0 is now available in black, shown above. No specs to this top have changed.
October 2018The Base 4.0 by Under Armour, priced at $85, is a synthetic form-fitting base layer best used in cold weather for traditional team sports, as opposed to outdoor recreational use. It is a very breathable top, dries reasonably quickly, and appears to have acceptable durability. However, it scored poorly in warmth, comfort, fit, and layering ability.
Despite having a low fabric density of 172 g/m², the Base 4.0 still weighed nine and a half pounds. This product didn't provide nearly the warmth as its merino wool competitors, but that's not necessarily a bad thing. For warmer temps or high-intensity workouts, a less insulating top is called for, but don't expect this shirt to do too well in the Arctic.
This product does have a drop tail for a cozier booty, as well as thumb straps. However, like the rest of this top, the thumb loops were too tight to be comfortable, and therefore rarely used. Furthermore, this was the only model that is singularly available in a crew cut, with no zip neck or hooded options that add more warmth.
The excellent breathability of this product benefits from its tight fit, which stretches and spreads the fabric out over the upper body. In turn, this creates large spaces for moisture to escape through into the outside air. Moreover, any sweat that does condense on the inner layer is quickly wicked away by the internal checkerboard pattern. The Base 4.0 proved to be one of the most breathable products in this review.
We found the Base 4.0 to be the least comfortable model amongst its other competitors in this review, but we'll start off with the positives. It doesn't itch whatsoever, and we didn't experience any chafing under the arms. And if you're into showing off your upper body, this product should be your top choice.
Now that we've covered the pros, on to the cons. This top is tight and physically restricting. It didn't stop of from raising our arms, but it did push back against upward movement and almost snapped our arms back down into a relaxed position. Also due to the tight fit, whenever this shirt moved into a different position, it stayed there instead of falling back into place.
We were continually readjusting the sleeves and waist of this base layer. We wished for longer sleeves. As the thumb loops caused discomfort when utilizing them, we pretty much avoided them all together. Even the neck fit too tightly, uncomfortably and constantly reminding us that it was there and leading to some chafing in extended use.
Under Armour was one of the first companies to popularize the tight fitting base layers that have become ubiquitous amongst athletic apparel companies. This popularity is difficult to understand given how uncomfortable this top is to wear. Lastly, regarding style, this top is best left under cover of other layers, unless there's someone you're trying to impress with your physique.
This contender lands in the middle of the pack regarding drying speed when we soaked it and hung it to dry. We expect this model to dry even faster when worn than when suspended from a clothes hanger. As the tight-fitting fabric stretches over the torso, its surface area contact to the air will increase and speed up the drying process.
The close fit that is great for increasing breathability and showing off your muscles limits layering ability. While this can be worn quite effectively as a next-to-skin layer, it is uncomfortable when worn over anything else.
Through our experiences with this product, we think the Under Armour commercials portray the best uses of this product pretty accurately; the Base 4.0 is designed for high intensity, low duration athletic activities like football, soccer, or other organized sports in cold weather. It will feel pretty great underneath a jersey during an outdoor winter match or game. Its strengths in breathability and wicking overshadow its deficiencies in comfort and layering, and using it during periods of high intensity will counteract its lack of insulation.
