Expedition Weight is the thickest version of Capilene, Patagonia’s well-established base layer fabric. In fact this garment is one of the warmest tested. Yet at the same time it’s very fast wicking and very light due to the construction of the fabric, which consists of a smooth jersey knit outer with an open grid of raised fleece on the inside. This means there’s not actually much fabric in contact with your skin so any moisture is quickly moved away. The fabric is soft and stretchy and the top is close-fitting without feeling restrictive. There’s a long zip for ventilation, a snug collar and thumb loops inside the cuffs to stop the sleeves riding up. In warm weather it’s easy to push the sleeves up. The odour control works well on a new garment. Patagonia says it’s been tested for fifty washes and doesn’t involve any heavy metals, unlike some antimicrobial treatments. For cold weather this is an excellent base layer. It can also be used as a second layer, worn over a thinner base layer. It’s warm enough to replace a thin fleece. The cost is quite high but this is a dual purpose garment.