The women's technical 150 ZONE Long Sleeve Half Zip by icebreaker is lightweight and breathable, making it a perfect base layer in the cold. The merino-nylon fabric is spun so that soft merino is next to your skin and durable nylon on the outside. Lycra is added for stretch. a zip neck collar regulates core temperatures. Merino mesh panels improve ventilation. Flatlock seams take away abrasion points. Raglan sleeves and underarm gussets improve mobility. The front and back hems are extended for more coverage.