I have two other pairs of thermal leggings from brands we know and each cost at least twice what I would for a pair of merino have paid. Technology. They're as good or better than anything I've ever worn and I won't look at more expensive brands again. They're almost identical in every way, keep you warm all day, insanely comfortable, breathable and there's no reason not to buy them. Yesterday we tested them on the slopes and they performed extremely well. Buy with confidence.