Plastic ear tags (all brands) are much easier to install if they are warm.Why? As the temperature drops below freezing plastic becomes less flexible (more stiff) and forcing the male point of a tag through the female takes many more lbs. of pressure (because the female must expand).
So if you care about your hands it’s a good idea to keep the tags above freezing in very cold weather. It takes very little to do this. One method is to simply store them while tagging in a small bucket, cardboard box or tool box with a lid alongside a sealed pop bottle full of warm water. The warm water will keep both the air and the tags warmer in the container.