XTM Men's Merino 230 Long Sleeve Thermal Top

Who it's for

This is the layer you put on first and take off last. At 230 gsm it is the mid-weight that works across most of the Australian year - warm enough under a shell in the alpine, breathable enough that you are not stripping it off the moment the sun comes out. If you own one base layer, this is the weight to own.

It is also the layer for multi-day trips, and that has nothing to do with warmth. Merino resists odour in a way synthetics do not, which is the difference between one shirt for a week and carrying three.

Fit and layering

A crew neck, cut to sit close enough to work as a next-to-skin layer without restricting. It layers cleanly under a fleece or a shell, and it is presentable enough on its own that it works as a shirt on the drive home.

Fabric and construction

100% fine Australian merino at 230 gsm. The reason wool beats synthetic here is that it works as a thermo-regulator rather than just an insulator - it moves moisture away as vapour and keeps working when damp, so it holds heat in the cold and sheds it when you are working hard. Fine-micron merino is what makes that comfortable next to skin; the itch people remember from wool is coarse fibre, not wool itself.

Care

Wash cool and dry flat rather than in a dryer. Merino needs washing far less often than synthetic base layers - airing it overnight resets it, which is the whole point on a long trip.