Smartwool
Smartwool Classic All-Season Merino Base Layer 1/4 Zip (men's)
- Weight: 7/10 How much it adds to your pack.
- Warmth: 5/10 How much the fabric insulates next to your skin. Heavier fabric is warmer and slower to dry.
Spring, summer and autumn hill days, and wild camps where nights stay above freezing
- Weight
- 184 g (not stated)
- Fabric weight
- 150 g/m²
- Fibre
- Blend
- Merino
- 88%
Where to buy
GO Outdoors £85 In stock. Free delivery. Black, size M. Member price £80 (not included). Free standard delivery on orders £80 and over.
View at shop: GO OutdoorsBlacks £85 In stock. Delivery £4.99. Black, size M. The shop calls it the Half-Zip Baselayer Top. Free delivery over £95.
View at shop: BlacksSmartwool £89.99 In stock. Free delivery. Black. Free delivery over £55; 30 days free returns.
View at shop: SmartwoolPrices checked 8 Nov 2026 on each shop's own page; shops can change them. We earn no commission on these links; shops are listed by price. More
Our ratings (out of 10)
1 to 10, compared with the whole market. Each says what it's based on. How we score
Weight
From maker's figures 7/10How much it adds to your pack. 7: Better than most.
184 g is in the 160–199 g band. The figure is in the product copy that Blacks, Millets and GO Outdoors give for this top, which they sell as the Half-Zip; none of them says which size. Adventure Alan lists the quarter zip at 193 g, also with no size. Both figures sit in the same band, so the score holds whichever is right. Smartwool's own UK and US pages give no weight.
Warmth
From maker's figures 5/10How much the fabric insulates next to your skin. Heavier fabric is warmer and slower to dry. 5: Does the job. Average for wild-camping gear.
Smartwool's US page lists the fabric as 150 g/m² (lightweight), the bottom of the 150–189 g/m² band: a three-season layer, not a winter one. Its UK page gives no g/m² figure.
In short
Good for
- Spring, summer and autumn hill days, and wild camps where nights stay above freezing
- A light merino layer for sleeping in and for layering under a fleece or insulated jacket
- Cool-weather walking where you want to vent heat without taking the top off
- Wearing the zip open on the climb and closed on the ridge
Strengths
- 184 g by the shop figure (size not stated), light for a zipped top
- 150 g/m² fabric with a nylon core, which Smartwool says makes it more durable than thin pure merino
- 1/4 zip lets you vent heat without taking the top off
- Flatlock seams and offset shoulder and side seams, which Smartwool says reduce chafing
- 88% merino with the merino against the skin, per Smartwool
Weaknesses
- No independent test of the quarter zip found, so comfort, odour and durability are estimates, not reviewed scores (the reviews we found are of the crew-neck top)
- Thin 150 g/m² fabric: reviewers of the crew-neck version expect thinning at cuffs, hems and underarms with hard use
- Not warm enough alone for winter hills: 150 g/m² is a lightweight fabric
- Smartwool's UK site gives no weight, and shops list this top as a "Half-Zip" (see sources), so check the name when ordering
- Warm gentle wash, and a low tumble dry at most
Sources
We haven't tested this ourselves. Every score comes from these specs, tests and reviews.
ShowHide sources (4)
- Smartwool UK: Men's Classic All-Season Merino Base Layer 1/4 Zip (price, fabric 88% merino, 12% nylon, features)
- Smartwool US: Men's Classic All-Season Merino Base Layer 1/4 Zip (lightweight, 150 g/m²)
- Blacks: Smartwool Men's Classic All-Season Merino Half-Zip Baselayer Top (shop copy gives weight 184 g, no size; the same top under the shop's name)
- Adventure Alan: Smartwool Classic All-Season Merino Quarter Zip review (193 g, no size given)