The Tuvegga Air shirt has two sides: one is smooth, and the other has a textured surface. The smooth side against the skin enhances breathability, while the textured side provides extra warmthchoose depending on the situation. - Merino wool naturally resists odor and stays warm even when damp - 99% merino wool, 1% elastane - Fabric weight 250g/m² - Fiber thickness 18.7 microns (fine fiber) - Machine washable on wool program Devold undergarments are treated with a natural compound made to protect the apparel from wool-eating insects. It has a gentle, citronella-style scent and is completely harmless to people. The treatment protects the garment for one year and its scent diminishes and fades away with airing the garment.