The Smartwool micro weight thermals work naturally with your body to keep you comfortable all year round. These next to skin base layers allow moisture vapour to pass through them on warm spring days, then as the nights get colder they get working to keep you nice and warm. The 100% merino Smartwool range are antimicrobial, are cut for styling with comfort and feature flat lock seams. They even retain their warmth when they are wet after a down pour!