One Size fits all We lined these mittens with warm Sherpa Fleece, and added a fold-down top so you can answer your phone on the go. merino wool Merino Wool is naturally thermoregulating and soft against your skin. Naturally thermoregulating Soft features Designed for: Office Travel Commute Cozy lining: Stretch Sherpa Fleece liner fabric feels soft against your skin and is two way stretch