SmartWool specializes in creating 100% merino wool activewear. I’ve worn some Smartwool clothing for a couple of years now, and it still looks new — it’s hasn’t piled or worn. The merino wool is much softer against the skin than regular wool, it feels similar to thick silk. Here’s some other reasons why I think merino wool is efficient: it’s an excellent insulator, it’s lightweight (warmest material by weight), it’s naturally moisture wicking, it doesn’t smell when wet (anti-microbial), it’s durable, washable, quiet (it doesn’t rustle when moved), flame-retardant, self-extinguishing, renewable and biodegradable.
SmartWool also recently announced it will pay New Zealand merino farmers a premium to end the practice of mulesing their sheep, see this article for more information.