Technical Base Layers

Merino

Merino regulates temperature, stays warm when damp and resists odour naturally, so it can be worn for days without washing. On its own it dries more slowly and is less hard-wearing, which is why our merino base layers use core-spun yarns or blend in nylon for stretch, strength and faster drying.

Synthetic

Synthetic is lighter and dries faster, which suits high output, heat and running. Ours use recycled fabric with an anti-odour treatment and UPF 40+ sun protection.

For a full comparison, read Merino vs Synthetic Base Layers: Which Is Right for You?

Choosing the right weight

Lightweight layers (around 110 to 150gsm) suit high output and warmer weather, and work as a t-shirt on their own.

Midweight layers (around 180gsm and up) add warmth for cold days and winter, under a mid layer and shell.

Fit and features

Fit. A base layer should sit close to the skin to move sweat effectively, without restricting movement.

Zip necks. A quarter zip vents heat on climbs and closes up to retain warmth when you stop.

Seams. Flatlock seams lie flat under pack straps and a harness, so they don't rub.

Layering. Your base layer works with what goes over it. Read the Mountain Layering Guide.

Is a base layer the same as thermal underwear?

They do a similar job: a warm, close-fitting layer next to the skin. A technical base layer is also built to move sweat away during activity, which is what keeps you warm when you stop.

Do I need a base layer in summer?

A lightweight base layer often is your summer t-shirt. A fast-drying synthetic or light merino top moves sweat better than cotton and adds sun protection.

Can I wear a merino base layer for several days?

Yes. Merino is naturally odour-resistant, which is why it is the usual choice for multi-day trips and expeditions.