Merino wool shirts are always part of my travel gear, I don't go anywhere without them. The two shirts in the photo are by Icebreaker and I've had them with me since day 1 of my round the world adventures. Other than some sweat stains (don't ever use anti-perspirants with aluminum, they will ruin the shirts) and a few really small holes, they've survived remarkably well to all the conditions I've put them through. The biggest advantage to merino wool is their no stink properties. Doing a 4 day trek in Patagonia, my clothes were all merino wool, 1 set for hiking and 1 set for sleeping. That's all! They never had that horrible smell you get with those quick dry, synthetic shirts after just a few hours of wear. I've since added more pieces to cover every travel condition, enough to handle a 12 day trek to Everest Base Camp, still following the same rule of 1 set for hiking and 1 set for sleeping. I still haven't found anything better than merino wool.