Merino wool is simultaneously insulating and cooling, varying with your body temp and the outdoor environment to keep you cool when it's warm and warm when it's cool.  It's also an amazing moisture manager, wicking sweat away from the body, drying quickly and never retaining odour.  It also has great elasticity so it won't lose it's shape.  So don't sweat it if you like to sweat.  Get active and know that we've go you covered.