250 GSM is our everyday cold-weather standard — warm enough for winter city days, breathable enough for the trail.
Fabric weight guide
Which merino weight is right for you?
GSM is grams per square metre — how much fabric there is, not a warmth rating. Every weight is the same soft 17.5-micron Australian merino: it wicks sweat before it turns cold, insulates when it is cold and ventilates when it is warm. Lighter fabric breathes and dries faster; heavier fabric holds more heat when you stop moving. Choose by season and by how hard you will be working.
Warm & hot · 60°F+ / 15°C+
Best for: summer hiking, running, cycling, hot-climate travel, everyday tees and office wear; the next-to-skin layer under a 250 when you work hard in winter
Pick this if: you want a shirt that stays fresh for days, dries in an hour and keeps you cooler than cotton in the heat — or you simply run hot
Think twice if: you will mostly be standing still in the cold; on its own a lightweight layer has little insulation to offer
Shop 165 GSM →Cool to mild · 40–65°F / 5–18°C
Best for: spring and autumn as a standalone top, summer evenings, cool-morning hikes and commutes; winter as a base under a mid-layer
Pick this if: you want one merino layer that covers most of the year, or you are unsure between light and mid — this is where most people should start
Think twice if: you run cold and your winter is genuinely cold: go straight to 250
Shop 190 GSM →Cold · 20–45°F / −7 to 7°C
Best for: skiing and snowboarding, winter hiking, cold-weather work, frosty autumn mornings; top-and-bottom sets so your legs are not the weak link
Pick this if: you run cold in fall, want the classic winter base layer, or spend active days below freezing under a shell
Think twice if: you overheat easily on hard uphill efforts — a 165 or 190 underneath, 250 over it, is the better system
Shop 250 GSM →Deep cold · below 20°F / −7°C
Best for: ice fishing, hunting stands, camp at altitude, winter mornings spent waiting rather than walking, a house that never quite gets warm
Pick this if: warmth matters more than breathability, you are chronically cold, or your winter involves long spells standing still outdoors
Think twice if: you will be working hard — it is too warm for a sweaty climb, which is exactly the point
Shop 320 GSM →A base layer works by sitting close to the skin, where it can move moisture — loose is not more comfortable, just slower. Between sizes? Size down for a next-to-skin layer under a shell, size up to wear it on its own or over another layer. Merino stretches with wear and springs back after a wash. Heavier weight is not itchier: itch comes from coarse fibre, and every weight here is the same superfine merino.
Size guide
Size Guide
Our merino has a close, next-to-skin fit by design. If you are between sizes, stay true to size for base-layer use or size up for a more relaxed everyday fit. Free returns within 30 days, so ordering two sizes and sending one back is completely fine.
How to measure
Chest — around the fullest part of your chest, with the tape level under the arms.
Waist — around your natural waistline, with the tape comfortably loose.
Hips — around the fullest part of your hips and seat.
Inside leg — from the top of your inner thigh to your ankle bone.
Measure over light clothing, keeping the tape snug but not tight. Tap any chart below to open it full size.
Men's Base Layer Set
Need different sizes for the top and the bottoms? Build your own set →
Women's Base Layer Set
Need different sizes for the top and the bottoms? Build your own set →
Kids' Base Layer Set
Men's T-Shirt
Women's T-Shirt
Men's Long Sleeve
Same body measurements across 165, 190, 250 and 320gsm.
Women's Long Sleeve
Kids' Long Sleeve
Men's Long Johns
Women's Thermal Leggings
Kids' Thermal Leggings
Men's Half Zip
Women's Half Zip
Merino Wool Socks
Beanies, snoods and balaclavas
Still unsure which size to pick? Email info@merinotech.co.uk with your height, chest and waist and we will recommend a size. Free UK delivery over £49 and free returns within 30 days.
- Free UK delivery over £49
- 30-day free returns
- Ships in 1–2 business days
Description
Merino Wool Half Zip Long Sleeve in the classic Black color.
Designed for both comfort and fashion, this long-sleeve top is perfect for a range of activities and occasions.
Crafted from 100% Merino wool, it offers exceptional warmth, moisture-wicking, and natural temperature regulation.
Merino wool's natural antimicrobial properties ensure odor resistance, and its soft touch against your skin guarantees a comfortable fit.
Whether you're hiking, running, or simply enjoying a casual outing, our Black Merino Wool Half Zip Long Sleeve combines function and style for a versatile addition to your wardrobe.
Care
Turn inside out. Machine wash cold on a gentle cycle with like colours and a wool-safe detergent. Do not bleach. Lay flat or hang to dry — do not tumble dry.
Shipping & returns
Free UK delivery on orders over £49. Orders ship within 1–2 business days. 30-day free returns on unworn items with tags attached.
Men's half-zip base layer
Zip up, zip down, stay comfortable
A quarter-length zip lets you dump heat on the climb and seal in warmth on the ridge. The stand collar protects your neck; the long body stays put under a pack.
Size guide
Men's Long Sleeve 320 ZIP
Fit
A close, next-to-skin fit that is true to size for a base layer. Between sizes? Stay true to size to wear it under other layers, or size up for a more relaxed fit on its own.
How to measure
- Chest – around the fullest part of your chest, tape level under the arms.
- Waist – around your natural waistline, tape comfortably loose.
- Hips – around the fullest part of your hips and seat.
- Inside leg – from the top of your inner thigh to your ankle bone.
Measure over light clothing and keep the tape snug but not tight. Still unsure? Email info@merinotech.co.uk with your height, chest and waist and we will recommend a size. Unworn items can be returned free within 30 days.
THE FABRIC
Why merino wool
Merino wool moves sweat away from your skin as vapour and lets it evaporate from the fabric, so you stay dry and comfortable whether you are hiking, commuting or skiing.
Merino fibres naturally resist the bacteria that cause odour, so you can wear a base layer for several days, on the trail or while travelling, and it still smells fresh.
Wool can absorb up to 30% of its weight in moisture without feeling wet. In damp British weather it keeps insulating where cotton and polyester leave you cold.
Merino absorbs UV radiation: our lightweight layers offer UPF 25 and the midweight and heavyweight options UPF 50+, handy on long days in the hills.
Merino wool is naturally hard to ignite and self-extinguishes without melting onto the skin, unlike synthetic base layers.
Merino is a natural, renewable and biodegradable fibre. Sheep grow a new fleece every year, and a worn-out merino garment breaks down instead of shedding plastic microfibres.
FAQ
Men's merino half-zips & hoodies: FAQ
What is this 320gsm half-zip base layer top best for?
It is a heavyweight 320gsm merino layer, best for deep cold, winter camping and ski days. Compare every weight in our merino weight guide.
Is this half-zip base layer top warm enough for skiing?
Yes. 320gsm heavyweight merino is our warmest weight, ideal under ski clothing in very cold resorts or if you feel the cold.
Why choose a half-zip merino top instead of a crew neck?
The zip lets you vent heat on a climb or in a warm pub and close it up against the wind when you stop, so one top covers a wider range of temperatures.
Is a merino half-zip a base layer or a mid layer?
Both. Worn next to the skin it is a warm base layer; over a lightweight merino T-shirt it works as a breathable mid layer under a waterproof.
Which weight of merino half-zip should I buy?
165gsm for active use and milder days, 250gsm for most winter walking and skiing, and 320gsm for cold, low-activity days. The 190gsm hoodie is a versatile everyday layer.
Should I size up for a half-zip or hoodie?
Take your usual size to wear it as a base layer. Size up if you plan to wear it over another top. See the size guide.
How do I care for a merino hoodie?
Zip it up, turn it inside out and wash at 30°C on a wool cycle, then dry flat. Do not tumble dry.
this is the best things i have ever wear in my life
test
Just returned from a trip to Iceland. This 320 weight zip was the only warm mid-layer I brought. By the glacier, simply added a lightweight long-sleeve under, and a shell over. Easy to pack for one-bag travel. Great for chilly mornings/evenings in town. Very satisfied.
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I have purchased many merino items as I love the feel, quality and price of your clothing. I live in Minnesota and wear wool, often in several layers, frequently. I also find the half zip versions great for the golf course.
I have purchased many merino items as I love the feel, quality and price of your clothing. I live in Minnesota and wear wool, often in several layers, frequently. I also find the half zip versions great for the golf course.
Smart, Good for outdoor and outings.
Smart, Good for outdoor and outings.
I bought a couple of Men's Merino Half Zip Long Sleeve 320 previously. After those, I bought more, and on this latest order, I bought 3. They are all very comfortable. The wool is much better quality than the previous ones I own from SmartWool and Ice Breaker. They keep me comfortable when it's cold outside, yet not too hot when it's like spring outside.
I bought a couple of Men's Merino Half Zip Long Sleeve 320 previously. After those, I bought more, and on this latest order, I bought 3. They are all very comfortable. The wool is much better quality than the previous ones I own from SmartWool and Ice Breaker. They keep me comfortable when it's cold outside, yet not too hot when it's like spring outside.
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Very impressed with this top. Wore mine under a dress shirt with my suit to a funeral in Tennessee. Temperature was 30 degrees with a 20 mph wind. Needless to say it was raw. My top kept me fairly comfortable.
Also the shipping was quick. I’ll be buying some more of these!
Very impressed with this top. Wore mine under a dress shirt with my suit to a funeral in Tennessee. Temperature was 30 degrees with a 20 mph wind. Needless to say it was raw. My top kept me fairly comfortable.
Also the shipping was quick. I’ll be buying some more of these!