And the details of this shirt make it incredibly comfortable when you move so it is an ideal baselayer under a top or shell and great for wearing alone on a cool morning run or a hike in the mountains flatlock seams won39t chaffe a drop hem for more coverage and set in sleeves keep it comfortable under a pack and because it is merino you can wear it several times between washings odour free why icebreaker merino the merino is an ancient breed of alpine sheep over millions of years