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Stio Basis PeakWool Midweight Half Zip Review

A heavier wool/synthetic blend base layer that packs a lot of durability along with comfort
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Stio Basis PeakWool Midweight Half Zip Review
Credit: Justin Simoni
Price:  $160 List
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Manufacturer:   Stio
Justin Simoni
By Justin Simoni ⋅ Review Editor  ⋅  April 1, 2026
77
OVERALL
SCORE


RANKED
#5 of 21
  • Warmth - 25% 7.0
  • Breathability - 20% 8.0
  • Comfort and Fit - 20% 8.0
  • Durability - 15% 8.5
  • Drying Speed - 10% 6.0
  • Layering Ability - 10% 9.0

Our Verdict

The Stio Basis PeakWool Midweight Half Zip is made for people who like a heavy-duty feeling base layer, with more durability than comparable 100% merino wool options. The inclusion of a synthetic blend in the wool keeps this base layer looking good and prevents the top from stretching out over time. Made for colder weather, the PeakWool is thick and tough enough to wear as a light mid-layer as well. The heavier fabric weight is perfect for wintry conditions and more static, stationary activities, but you may find it too warm for shoulder-season duties.
REASONS TO BUY
Synthetic blend fabric more durable than 100% merino wool
Tough half zipper for themo-regulation
High collar to lock in warmth
"sweatshirt-like"" comfort
REASONS TO AVOID
Heavy fabric doesn't necessarily equate to being warmer
Slow drying speed on the line
Expensive

Our Analysis and Test Results

A super comfortable and thick wool/synthetic blend fabric defines the Stio Basis PeakWool Midweight Half Zip, destined to keep the wearer warm despite cold weather. A high collar and thumb loops help to seal in heat, while the half-length zipper helps quickly dump out surplus heat. Quality is obvious anywhere you look on the PeakWool, from the flatlock seams used throughout to the comfortable panel shoulder design.

stio basis peakwool midweight half zip - the stio basis peakwool midweight half zip excels on cold days out.
The Stio Basis PeakWool Midweight Half Zip excels on cold days out.   Credit: Justin Simoni

Likes


The varied synthetic/wool blend (56% Merino Wool, 23% Tencel, 12% Recycled Nylon, 7% Nylon, 2% Spandex) of the Stio Basis PeakWool Midweight Half Zip fabric is spun up to a heavy 280 g/ms weight, making it extremely comfortable to wear. The fabric blend that includes nylon for strength and a little elastane for stretch should keep its shape better than a 100% merino top throughout its life.

stio basis peakwool midweight half zip - the half-zip was critical in some circumstances to thermoregulate.
The half-zip was critical in some circumstances to thermoregulate.   Credit: Justin Simoni

We enjoyed many of the details found throughout that enhance its comfort, like the burly half-zipper, which helps thermoregulate, and the high collar and thumb loops at the cuffs, which help lock in heat.


Layering ability is also top-notch. Piling additional layers on top is a sure way to craft a great winter layer system for cold weather, and the PeakWool Midweight is reasonably durable enough to be worn all by itself, with a look refined and finished enough to be appropriate for casual public outings.

stio basis peakwool midweight half zip - the thumbs at the end of the sleeves show off the flatlock-seam...
The thumbs at the end of the sleeves show off the flatlock-seam construction found throughout the Stio Basis PeakWool Midweight Half Zip.   Credit: Justin Simoni

Dislikes


Like many other heavier base layers, the dry time on the line for the Stio Basis PeakWool Midweight Half Zip isn't great; this top took longer than most to fully dry. Heavier fabric and its tight weave absorb more moisture, which then takes longer to naturally evaporate.


This also usually suggests that if you do get sweaty while wearing the PeakWool Midweight, it'll also take a while to get dry, and a wet base layer is just colder and more clammy than a drier one.

Our climate-controlled workout sessions wearing the Stio Basis PeakWool Midweight Half Zip got us plenty hot and sweaty, but compared to other base layers, this one wasn't as warm as the fabric weight would have us guess.   Credit: Justin Simoni

And despite its heavier weight, our workout tests didn't indicate that the Stio Basis PeakWool Midweight Half Zip punched above its weight class when it comes to warmth, only being slightly above average when compared to our entire lineup. What you do get for the weight is, instead, seemingly endless comfort and durability.


Coming in at 13.1 ounces for a size “large”, the Stio Basis could very well be too much base layer for some applications once the mercury starts to rise. Keep this base layer close at hand when the flakes start to fly, and the ropes for the new groomers start to drop.

stio basis peakwool midweight half zip - the stio basis peakwool midweight half zip makes an excellent base...
The Stio Basis PeakWool Midweight Half Zip makes an excellent base for your cold weather layering system which could include a midlayer fleece and a synthetic insulation outer layer.   Credit: Justin Simoni

Should you Buy the Stio Basis PeakWool Midweight Half Zip?


Heavier base layers are undoubtedly warm and comfy, and the Stio Basis PeakWool Midweight Half Zip is no exception. The PeakWool works best as a base layer in cold, wintry conditions. We would suggest it over a 100% merino base layer of a similar weight if you're worried about durability in the long run. This is a top-tier base layer with exceptional stitchwork and quality, ready to support you during cold-weather adventures on the tops of mountains or right next to the lodge's fireplace with your favorite book.

stio basis peakwool midweight half zip - great the cold weather wearing the stio basis peakwool midweight...
Great the cold weather wearing the Stio Basis PeakWool Midweight Half Zip!   Credit: Justin Simoni

What Other Base Layers Should You Consider?


The Smartwool Classic All-Season Merino 1/4 Zip is a cold-weather all-star, made with 100% merino wool spun up to a 250 g/sm weight. Treated with care, it's hard to beat for colder activities. The Arc'teryx Rho LT Crew is a fully synthetic base layer that nips at the toes of wool options, but is far more durable, perfect for those hard on their gear. A more budget-friendly option is the Meriwool Merino 250 Long Sleeve, a good introduction to heavier merino wool base layers.

Side-by-Side Comparison
Compare Stio Basis PeakWool Midweight Half Zip versus top competing products:
 
Awards  
Price $160 List
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Overall Score Sort Icon
77
Star Rating
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Bottom Line A heavier wool/synthetic blend base layer that packs a lot of durability along with comfort
Pros Synthetic blend fabric more durable than 100% merino wool, tough half zipper for themo-regulation, high collar to lock in warmth, "sweatshirt-like"" comfort
Cons Heavy fabric doesn't necessarily equate to being warmer, slow drying speed on the line, expensive
Rating Categories Stio Basis PeakWool...
Warmth (25%)
7.0
Breathability (20%)
8.0
Comfort and Fit (20%)
8.0
Durability (15%)
8.5
Drying Speed (10%)
6.0
Layering Ability (10%)
9.0
Specifications Stio Basis PeakWool...
Fabric Weight Class Heavyweight
Material 56% Merino Wool, 23% TENCEL™, 12% Recycled Nylon, 7% Nylon, 2% Spandex
Fit Loose
Odor Control Fabric Naturally odor resistant
Time to Air Dry 65 min
Thumb Loops Yes
Dryer Safe Yes, tumble dry low
UPF Sun Protection None listed
Seam Stitching Flatlock seams
Shoulder Top Seams No
Drop Tail Hem No
Measured Weight (Size Large) 13.1 oz
Measured Shirt Length (Size Large) 26.0 in
Available Cuts Crew, Half-Zip, Hoodie
Or, compare up to 5 products side-by-side here.
Justin Simoni