Smartwool’s base layer long sleeved tops are made of 100% merino wool. They are non-itchy, form fitting, and have natural anti-odor properties. They also provide superior moisture management and temperature regulation. Interestingly, wool can absorb 30% of its weight in sweat and still feel dry to your skin. Additionally, all the tops provide UPF protection from the sun.


Smartwool offers three weights in their base layer tops, microweight, lightweight, and midweight. The microweight tops can be worn year round, in summer they will provide good sun protection while maintaining breathability and moisture management. The midweight layer is the heaviest Smartwool offers and it is perfect for a cold weather base layer. I have all three weights that I use when backpacking. I get the most use out of my midweight layer as I sleep in it when camping and use it on cold day hikes as well.

Styles & Fit

The shirts usually come in either v-neck, crew neck, or half zip fronts in both men’s and women’s fits. As a top layer Smartwool tops are form fitted so if you have a slim physique you can comfortably wear the base layer as your only layer. However, if you are carrying any extra pounds they will be highlighted by the snug fit of these tops. Don’t rule them out though, as an against the skin layer they are awesome and you can just throw a mid-layer on top of them if they are too curve-hugging! Women can also purchase the men’s tops if they prefer a roomier fit.


Smartwool Microweight shirts offer a UPF of 30, they are the lightest weight of the base layers and may have you wondering if it’s going to be thick enough when you open the package. Don’t worry; it’s a great choice as a standalone garment in warm weather when your activities warrant some sun protection, moisture wicking and odor control. The fit seems true to size. Be aware some think the microweight is a bit sheer. The Microweight Zip Top offers a 10 inch neck zipper for men and an 8 inch zipper in the women’s style that allows you to vent before you become overheated. The crew neck top is available for men and women while the V neck style is available in Women’s sizing only.


Smartwool Lightweight tops come in several styles. For men there is a crew neck, sportknit crew, mock turtle neck, zip neck and zip neck hoody both with 12 inch zipper. Women’s styles are crew, zip neck with 12 inch zipper, asymmetrical zip neck with thumb holes, and asymmetrical zip hoody. The lightweight style offers a 35 UPF sun protection along with 100% merino wool for superior moisture control, odor control, body heat regulation, and non-itch comfort.


Smartwool midweight tops are the heaviest style Smartwool offers in a base layer. They offer 50+ UPF sun protections, along with 100% merino wool for superior moisture control, odor control, body heat regulation, and non-itch comfort. Women’s styles come in crew neck, pattern crew, mock turtle neck, zip neck (8″ zip), pattern zip neck (8″), funnel zip (15″ zip), and hoody zip neck (13″ zip). Men’s styles are crew neck, pattern crew, zip neck, funnel zip neck (14.5″ zip), mock turtle neck, and zip neck hoody (14.5″ zip).