The Icebreaker 200 Oasis crew is the base layer for a walker who sweats on the climb and feels the cold at the top.
The pick for most walkers is the Icebreaker 200 Oasis Long Sleeve Crewe, sold for men and women.
It is 100% merino wool at 200 g/m², with flatlock seams, offset shoulder seams and gussets under the arms.
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The four tops, at a glance:
- Icebreaker 200 Oasis Long Sleeve Crewe, men’s, and the women’s version, 200 g/m², the default for most days
- Icebreaker 200 Oasis Long Sleeve Half Zip, men’s, the same 200 g/m² fabric with a half-length front zip
- Smartwool Classic Thermal Merino Crew, men’s, a thick, warming merino top from a second brand
- Helly Hansen LIFA Merino Midweight Crew, men’s, merino outside and polypropylene inside
| Your day out | What to carry |
|---|---|
| You want one top for most days, in men's or women's | Icebreaker 200 Oasis Long Sleeve Crewe |
| You want a front zip to vent at the steep part | Icebreaker 200 Oasis Long Sleeve Half Zip |
| You want a thick, warming merino top from a second brand | Smartwool Classic Thermal Merino Crew |
| You want merino outside and polypropylene against the skin | Helly Hansen LIFA Merino Midweight Crew |
Icebreaker 200 Oasis Long Sleeve Crewe
You want one merino top for most walking days, and you want it in a men's or a women's cut
Icebreaker Men's 200 Oasis Long Sleeve Crewe 100% merino wool, 200 g/m²Flatlock seams, offset shoulder seams, gussets Read the full specification on Amazon Icebreaker Women's 200 Oasis Long Sleeve Crewe 100% merino wool, 200 g/m²Flatlock seams, offset shoulder seams, gussets Read the full specification on AmazonThis is the first pick because it is the one top here sold for both men and women at 200 g/m². The cut is slim, and the men’s listing gives a fibre diameter of 18.9 micron.
Flatlock seams, offset shoulder seams and underarm gussets are all listed.
The fabric is sold as breathable, odour resistant and temperature regulating.
Best for: a walker who wants one base layer for most days, men’s or women’s.
Icebreaker 200 Oasis Long Sleeve Half Zip
You want the 200 g/m² fabric with a front zip to open on the steep climb
Icebreaker Men's 200 Oasis Long Sleeve Half Zip 100% merino wool, 200 g/m²Half-length front zip, flatlock seams Read the full specification on AmazonIt is the same 100% wool, 200 g/m² fabric as the crew, with a half-length front zip.
Of the four tops here it is the only one listed with a zip.
A zip lets you open the neck without taking a layer off.
It also has flatlock seams, offset shoulder seams and gussets, in a slim fit.
Best for: a man who wants to vent at the neck on the climb and close it at the top.
Smartwool Classic Thermal Merino Crew
You want a thick, warming merino top from a second brand, in a men's cut
Smartwool Men's Classic Thermal Merino Base Layer Crew 100% merino woolSlim athletic cut, flatlock seams staggered to prevent chafing Read the full specification on AmazonThe listing gives 100% wool, a slim, close-fitting cut and flatlock seams staggered to prevent chafing. It describes thick, soft merino with warming, breathable and odour-inhibiting properties, for skiing and hillwalking.
No fabric weight is published for this top.
Best for: a man who wants a thick, warming merino top from a second brand.
Helly Hansen LIFA Merino Midweight Crew
You want merino on the outside and a synthetic fibre against the skin
Helly Hansen Men's LIFA Merino Midweight Crew 2-layer: merino wool outside, LIFA insideFlat lock seams Read the full specification on AmazonThis is a two-layer top, with a 100% merino wool exterior and a fibre content of 57% merino wool and 43% polypropylene.
Helly Hansen describes it as pairing the warmth of merino with the moisture management of its LIFA fibres.
It is the only top of the four that is not 100% merino, because the inner layer is polypropylene.
Best for: a man who wants a merino face with a synthetic layer next to the skin.
What merino does and does not do
Retailer listings describe merino as breathable, odour resistant, and temperature and moisture regulating.
It is a base layer, so it does nothing against rain or wind.
The shell you carry over it does that.
The women’s 200 Oasis and the Smartwool care lists both say machine wash at 30°C and no bleach. The Oasis list adds no fabric softener and no tumble drying, and the Smartwool list adds no chemical cleaning.
What the g/m² figure means
The figure is the weight of one square metre of the fabric, in grams.
A higher number means thicker cloth.
The Oasis tops are 200 g/m².
The Smartwool has no published fabric weight, and the Helly Hansen is sold as midweight (210 - 280), a band rather than one figure.
Which weight for which day
The Smartwool is the top here sold for cold winter days.
- Most walking days: a 200 g/m² crew, or the half zip to vent at the neck.
- Cold days, or if you feel the cold more than most: the Smartwool Classic Thermal.
- Merino outside and a synthetic fibre inside: the Helly Hansen LIFA Merino Midweight.
- Rain or strong wind: the base layer is not the answer, so carry a shell.
Wash the Helly Hansen inside out, with wool detergent, and do not wring it.
For the layer that goes over the top, read about a waterproof jacket, and for the rest of the bag, what to pack. Check the mountain weather for the tops before you choose.
We compile and explain public route and safety information. We guide nobody and sell nothing on the hill.
Which top to put on, by walker
For most days, a man buys the Icebreaker 200 Oasis Long Sleeve Crewe and a woman buys the women’s Icebreaker 200 Oasis crew.
On a colder day, a man can choose the Smartwool Classic Thermal.
If you already own a base layer that dries and does not rub, you do not need to buy another yet.
