What is the UP Ear Warmer? A close-fitting ear warmer, specially designed to keep a runners ears warm & dry in the coldest weather. When can I use it? Wear for running, racing & other sporting activities in cold, wet & windy conditions. What size is it? Four-way stretch material means one size fits most. How does it work? The UP warmer is specially shaped to cover only the ears & the four-way stretch material ensures a snug, but comfortable fit. The component yarns of this Ear Warmer make the exterior resistant to abrasion & pilling, whilst the polyester interior has both insulation & wicking properties.