This premium base layer features soft, lightweight 17.5-micron Merino wool sourced from ethical farms. Designed for trail runners, it offers natural temperature regulation, moisture management, and odor resistance. Offset shoulder seams prevent chafing under packs, while underarm mesh panels boost breathability. Integrated thumbholes keep sleeves in place, and reflective details improve visibility in low light. Machine washable and durable, it maintains shape for frequent use.