The updated slim fit optimises layering performance & next-to-skin comfort, & Icebreaker have also added offset shoulder seams & forward set side seams to reduce chafing when you’re wearing a pack or moving fast. The half-zip design also makes for easy temperature regulation during high-output days or variable temperatures. The merino fibres also resist the build up of odour for multi day freshness. Why Icebreaker Merino? The merino is an ancient breed of alpine sheep. Over millions of years they evolved a superfine, highly breathable fleece to protect them from freezing winters & scorching summers. It will do the same for you. TEMP CONTROL Merino naturally keeps you warm in cold weather & cool in warm weather. BREATHABLE Merino absorbs & releases vapour to prevent overheating & clamminess. UV PROTECTION Merino gives you extra protection against the suns harmful rays, naturally. NO ODOUR Naturally anti-bacterial, it can be worn for days on end without washing.