This is the "go to" when it gets a little warmer. We designed this a technically a base layer, but it is awesome as an exterior piece during the spring and summer. The CORDURA®/Merino intimate-blend fabric is uniquely durable and amazingly breathable, regulating your body’s "Micro-Climate" all year around. The reinforced shoulder makes it great for backpacking without the worry of wearing out the fabric. Slim fit, so bump up a size if you want a little extra room.